diff --git a/adminfront/src/app/routes.tsx b/adminfront/src/app/routes.tsx
index 8cd13cf1..96bde96f 100644
--- a/adminfront/src/app/routes.tsx
+++ b/adminfront/src/app/routes.tsx
@@ -6,7 +6,11 @@ import AuditLogsPage from "../features/audit/AuditLogsPage";
 import AuthPage from "../features/auth/AuthPage";
 import DashboardPage from "../features/dashboard/DashboardPage";
 import GlobalOverviewPage from "../features/overview/GlobalOverviewPage";
+import TenantGroupCreatePage from "../features/tenant-groups/routes/TenantGroupCreatePage";
+import TenantGroupDetailPage from "../features/tenant-groups/routes/TenantGroupDetailPage";
 import TenantGroupListPage from "../features/tenant-groups/routes/TenantGroupListPage";
+import TenantGroupProfileTab from "../features/tenant-groups/routes/TenantGroupProfileTab";
+import TenantGroupTenantsTab from "../features/tenant-groups/routes/TenantGroupTenantsTab";
 import TenantCreatePage from "../features/tenants/routes/TenantCreatePage";
 import TenantDetailPage from "../features/tenants/routes/TenantDetailPage";
 import TenantListPage from "../features/tenants/routes/TenantListPage";
@@ -32,6 +36,15 @@ export const router = createBrowserRouter(
         { path: "tenants", element: <TenantListPage /> },
         { path: "tenants/new", element: <TenantCreatePage /> },
         { path: "tenant-groups", element: <TenantGroupListPage /> },
+        { path: "tenant-groups/new", element: <TenantGroupCreatePage /> },
+        {
+          path: "tenant-groups/:id",
+          element: <TenantGroupDetailPage />,
+          children: [
+            { index: true, element: <TenantGroupProfileTab /> },
+            { path: "tenants", element: <TenantGroupTenantsTab /> },
+          ],
+        },
         {
           path: "tenants/:tenantId",
           element: <TenantDetailPage />,
diff --git a/adminfront/src/features/tenant-groups/routes/TenantGroupCreatePage.tsx b/adminfront/src/features/tenant-groups/routes/TenantGroupCreatePage.tsx
new file mode 100644
index 00000000..ccbd63e5
--- /dev/null
+++ b/adminfront/src/features/tenant-groups/routes/TenantGroupCreatePage.tsx
@@ -0,0 +1,142 @@
+import { useMutation } from "@tanstack/react-query";
+import type { AxiosError } from "axios";
+import { LayoutGrid, Sparkles } from "lucide-react";
+import { useState } from "react";
+import { useNavigate } from "react-router-dom";
+import { Badge } from "../../../components/ui/badge";
+import { Button } from "../../../components/ui/button";
+import {
+  Card,
+  CardContent,
+  CardDescription,
+  CardHeader,
+  CardTitle,
+} from "../../../components/ui/card";
+import { Input } from "../../../components/ui/input";
+import { Label } from "../../../components/ui/label";
+import { Textarea } from "../../../components/ui/textarea";
+import { createTenantGroup } from "../../../lib/adminApi";
+
+function TenantGroupCreatePage() {
+  const navigate = useNavigate();
+  const [name, setName] = useState("");
+  const [slug, setSlug] = useState("");
+  const [description, setDescription] = useState("");
+
+  const mutation = useMutation({
+    mutationFn: () =>
+      createTenantGroup({
+        name,
+        slug: slug || name.toLowerCase().replace(/ /g, "-"),
+        description: description || undefined,
+      }),
+    onSuccess: () => {
+      navigate("/tenant-groups");
+    },
+  });
+
+  const errorMsg = (mutation.error as AxiosError<{ error?: string }>)?.response
+    ?.data?.error;
+
+  return (
+    <div className="space-y-8">
+      <header className="space-y-2">
+        <div className="flex items-center gap-2 text-sm text-[var(--color-muted)]">
+          <span>Tenants</span>
+          <span>/</span>
+          <span>Groups</span>
+          <span>/</span>
+          <span className="text-foreground">Create</span>
+        </div>
+        <div className="flex flex-wrap items-center justify-between gap-3">
+          <div>
+            <h2 className="text-3xl font-semibold">테넌트 그룹 추가</h2>
+            <p className="text-sm text-[var(--color-muted)]">
+              여러 테넌트를 논리적으로 묶어 관리하기 위한 그룹을 생성합니다.
+            </p>
+          </div>
+          <Badge variant="muted">Super Admin only</Badge>
+        </div>
+      </header>
+
+      <Card className="bg-[var(--color-panel)]">
+        <CardHeader>
+          <CardTitle className="flex items-center gap-2">
+            <LayoutGrid size={18} className="text-primary" />
+            Group Profile
+          </CardTitle>
+          <CardDescription>
+            그룹 이름과 식별자(Slug)를 입력합니다.
+          </CardDescription>
+        </CardHeader>
+        <CardContent className="space-y-4">
+          <div className="space-y-2">
+            <Label className="text-sm font-semibold">
+              Group Name <span className="text-destructive">*</span>
+            </Label>
+            <Input 
+              value={name} 
+              onChange={(e) => setName(e.target.value)} 
+              placeholder="예: 바론소프트웨어 통합그룹"
+            />
+          </div>
+          <div className="space-y-2">
+            <Label className="text-sm font-semibold">Slug</Label>
+            <Input
+              value={slug}
+              onChange={(e) => setSlug(e.target.value)}
+              placeholder="baron-group"
+            />
+            <p className="text-xs text-muted-foreground">
+              URL이나 API에서 사용될 고유 식별자입니다. 비워두면 이름 기반으로 자동 생성됩니다.
+            </p>
+          </div>
+          <div className="space-y-2">
+            <Label className="text-sm font-semibold">Description</Label>
+            <Textarea
+              rows={3}
+              value={description}
+              onChange={(e) => setDescription(e.target.value)}
+              placeholder="그룹에 대한 설명을 입력하세요."
+            />
+          </div>
+
+          {errorMsg && (
+            <div className="rounded-lg border border-destructive/40 bg-destructive/10 px-3 py-2 text-sm text-destructive">
+              {errorMsg}
+            </div>
+          )}
+        </CardContent>
+      </Card>
+
+      <Card className="bg-[var(--color-panel)]">
+        <CardHeader>
+          <CardTitle className="flex items-center gap-2">
+            <Sparkles size={18} />
+            권한 상속 안내
+          </CardTitle>
+          <CardDescription>
+            테넌트 그룹의 관리자는 소속된 모든 테넌트에 대한 관리 권한을 자동으로 가집니다.
+          </CardDescription>
+        </CardHeader>
+        <CardContent className="text-sm text-[var(--color-muted)]">
+            생성 후 상세 페이지에서 테넌트를 이 그룹에 할당할 수 있습니다.
+        </CardContent>
+      </Card>
+
+      <div className="flex items-center justify-end gap-3">
+        <Button variant="outline" onClick={() => navigate("/tenant-groups")}>
+          취소
+        </Button>
+        <Button
+          onClick={() => mutation.mutate()}
+          disabled={mutation.isPending || name.trim() === ""}
+        >
+          생성
+        </Button>
+      </div>
+    </div>
+  );
+}
+
+export default TenantGroupCreatePage;
diff --git a/adminfront/src/features/tenant-groups/routes/TenantGroupDetailPage.tsx b/adminfront/src/features/tenant-groups/routes/TenantGroupDetailPage.tsx
new file mode 100644
index 00000000..83b22ae7
--- /dev/null
+++ b/adminfront/src/features/tenant-groups/routes/TenantGroupDetailPage.tsx
@@ -0,0 +1,77 @@
+import { useQuery } from "@tanstack/react-query";
+import { ArrowLeft, LayoutGrid } from "lucide-react";
+import { Link, Outlet, useLocation, useParams } from "react-router-dom";
+import { Badge } from "../../../components/ui/badge";
+import { fetchTenantGroup } from "../../../lib/adminApi";
+
+function TenantGroupDetailPage() {
+  const { id } = useParams<{ id: string }>();
+  const location = useLocation();
+
+  const groupQuery = useQuery({
+    queryKey: ["tenant-group", id],
+    queryFn: () => fetchTenantGroup(id!),
+    enabled: !!id,
+  });
+
+  const isTenantsTab = location.pathname.endsWith("/tenants");
+
+  return (
+    <div className="space-y-8">
+      <header className="flex flex-wrap items-start justify-between gap-4">
+        <div className="space-y-2">
+          <div className="flex items-center gap-2 text-sm text-[var(--color-muted)]">
+            <Link to="/tenant-groups" className="inline-flex items-center gap-2 hover:text-foreground">
+              <ArrowLeft size={14} />
+              Groups
+            </Link>
+            <span>/</span>
+            <span className="text-foreground">Detail</span>
+          </div>
+          <div className="flex items-center gap-3">
+            <div className="p-2 bg-primary/10 rounded-lg">
+                <LayoutGrid size={24} className="text-primary" />
+            </div>
+            <h2 className="text-3xl font-semibold">
+                {groupQuery.data?.name ?? "Loading Group..."}
+            </h2>
+          </div>
+          <p className="text-sm text-[var(--color-muted)]">
+            {groupQuery.data?.description || "그룹 정보를 관리하고 소속 테넌트를 구성합니다."}
+          </p>
+        </div>
+        <Badge variant="muted">Super Admin only</Badge>
+      </header>
+
+      {/* Tabs */}
+      <div className="flex border-b border-border">
+        <Link
+          to={`/tenant-groups/${id}`}
+          className={`px-6 py-3 text-sm font-medium transition-colors ${
+            !isTenantsTab
+              ? "border-b-2 border-primary text-primary"
+              : "text-muted-foreground hover:text-foreground"
+          }`}
+        >
+          기본 정보
+        </Link>
+        <Link
+          to={`/tenant-groups/${id}/tenants`}
+          className={`px-6 py-3 text-sm font-medium transition-colors ${
+            isTenantsTab
+              ? "border-b-2 border-primary text-primary"
+              : "text-muted-foreground hover:text-foreground"
+          }`}
+        >
+          소속 테넌트 ({groupQuery.data?.tenants?.length ?? 0})
+        </Link>
+      </div>
+
+      <div className="mt-6">
+        <Outlet context={{ group: groupQuery.data, refetch: groupQuery.refetch }} />
+      </div>
+    </div>
+  );
+}
+
+export default TenantGroupDetailPage;
diff --git a/adminfront/src/features/tenant-groups/routes/TenantGroupProfileTab.tsx b/adminfront/src/features/tenant-groups/routes/TenantGroupProfileTab.tsx
new file mode 100644
index 00000000..6ca74fb0
--- /dev/null
+++ b/adminfront/src/features/tenant-groups/routes/TenantGroupProfileTab.tsx
@@ -0,0 +1,97 @@
+import { useMutation, useQueryClient } from "@tanstack/react-query";
+import type { AxiosError } from "axios";
+import { useState } from "react";
+import { useOutletContext } from "react-router-dom";
+import { Button } from "../../../components/ui/button";
+import {
+  Card,
+  CardContent,
+  CardDescription,
+  CardHeader,
+  CardTitle,
+} from "../../../components/ui/card";
+import { Input } from "../../../components/ui/input";
+import { Label } from "../../../components/ui/label";
+import { Textarea } from "../../../components/ui/textarea";
+import { updateTenantGroup, type TenantGroupSummary } from "../../../lib/adminApi";
+
+function TenantGroupProfileTab() {
+  const { group, refetch } = useOutletContext<{ 
+    group: TenantGroupSummary; 
+    refetch: () => void 
+  }>();
+  const queryClient = useQueryClient();
+
+  const [name, setName] = useState(group?.name ?? "");
+  const [description, setDescription] = useState(group?.description ?? "");
+
+  const mutation = useMutation({
+    mutationFn: () => updateTenantGroup(group.id, { name, description }),
+    onSuccess: () => {
+      refetch();
+      queryClient.invalidateQueries({ queryKey: ["tenant-groups"] });
+    },
+  });
+
+  const errorMsg = (mutation.error as AxiosError<{ error?: string }>)?.response
+    ?.data?.error;
+
+  if (!group) return null;
+
+  return (
+    <div className="max-w-2xl space-y-6">
+      <Card className="bg-[var(--color-panel)]">
+        <CardHeader>
+          <CardTitle>그룹 정보 수정</CardTitle>
+          <CardDescription>
+            그룹의 기본 이름과 설명을 변경할 수 있습니다. 식별자(Slug)는 변경할 수 없습니다.
+          </CardDescription>
+        </CardHeader>
+        <CardContent className="space-y-4">
+          <div className="space-y-2">
+            <Label>그룹 ID (고유 식별자)</Label>
+            <Input value={group.id} disabled className="bg-muted" />
+          </div>
+          <div className="space-y-2">
+            <Label>Slug</Label>
+            <Input value={group.slug} disabled className="bg-muted" />
+          </div>
+          <div className="space-y-2">
+            <Label htmlFor="groupName">Group Name</Label>
+            <Input
+              id="groupName"
+              value={name}
+              onChange={(e) => setName(e.target.value)}
+            />
+          </div>
+          <div className="space-y-2">
+            <Label htmlFor="groupDesc">Description</Label>
+            <Textarea
+              id="groupDesc"
+              rows={4}
+              value={description}
+              onChange={(e) => setDescription(e.target.value)}
+            />
+          </div>
+
+          {errorMsg && (
+            <div className="rounded-lg border border-destructive/40 bg-destructive/10 px-3 py-2 text-sm text-destructive">
+              {errorMsg}
+            </div>
+          )}
+
+          <div className="flex justify-end pt-4">
+            <Button
+              onClick={() => mutation.mutate()}
+              disabled={mutation.isPending || (name === group.name && description === group.description)}
+            >
+              {mutation.isPending ? "저장 중..." : "변경사항 저장"}
+            </Button>
+          </div>
+        </CardContent>
+      </Card>
+    </div>
+  );
+}
+
+export default TenantGroupProfileTab;
diff --git a/adminfront/src/features/tenant-groups/routes/TenantGroupTenantsTab.tsx b/adminfront/src/features/tenant-groups/routes/TenantGroupTenantsTab.tsx
new file mode 100644
index 00000000..7dee5408
--- /dev/null
+++ b/adminfront/src/features/tenant-groups/routes/TenantGroupTenantsTab.tsx
@@ -0,0 +1,200 @@
+import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
+import { Plus, Trash2, Building2, Search } from "lucide-react";
+import { useState } from "react";
+import { useOutletContext } from "react-router-dom";
+import { Button } from "../../../components/ui/button";
+import {
+  Card,
+  CardContent,
+  CardDescription,
+  CardHeader,
+  CardTitle,
+} from "../../../components/ui/card";
+import {
+  Table,
+  TableBody,
+  TableCell,
+  TableHead,
+  TableHeader,
+  TableRow,
+} from "../../../components/ui/table";
+import { Input } from "../../../components/ui/input";
+import { Badge } from "../../../components/ui/badge";
+import { 
+    addTenantToGroup, 
+    removeTenantFromGroup, 
+    fetchTenants, 
+    type TenantGroupSummary 
+} from "../../../lib/adminApi";
+
+function TenantGroupTenantsTab() {
+  const { group, refetch } = useOutletContext<{ 
+    group: TenantGroupSummary; 
+    refetch: () => void 
+  }>();
+  const queryClient = useQueryClient();
+  const [searchTerm, setSearchTerm] = useState("");
+
+  // 전체 테넌트 목록 (할당용)
+  const tenantsQuery = useQuery({
+    queryKey: ["tenants", { limit: 100 }],
+    queryFn: () => fetchTenants(100, 0),
+  });
+
+  const addMutation = useMutation({
+    mutationFn: (tenantId: string) => addTenantToGroup(group.id, tenantId),
+    onSuccess: () => {
+      refetch();
+      queryClient.invalidateQueries({ queryKey: ["tenant-group", group.id] });
+    },
+  });
+
+  const removeMutation = useMutation({
+    mutationFn: (tenantId: string) => removeTenantFromGroup(group.id, tenantId),
+    onSuccess: () => {
+      refetch();
+      queryClient.invalidateQueries({ queryKey: ["tenant-group", group.id] });
+    },
+  });
+
+  const handleAddTenant = (tenantId: string) => {
+    addMutation.mutate(tenantId);
+  };
+
+  const handleRemoveTenant = (tenantId: string) => {
+    if (window.confirm("이 테넌트를 그룹에서 제외할까요?")) {
+      removeMutation.mutate(tenantId);
+    }
+  };
+
+  const availableTenants = tenantsQuery.data?.items.filter(
+    (t) => !group.tenants?.some((gt) => gt.id === t.id)
+  ) || [];
+
+  const filteredAvailable = availableTenants.filter(
+    (t) => t.name.toLowerCase().includes(searchTerm.toLowerCase()) || 
+           t.slug.toLowerCase().includes(searchTerm.toLowerCase())
+  );
+
+  return (
+    <div className="grid gap-6 lg:grid-cols-2">
+      {/* 현재 소속 테넌트 */}
+      <Card className="bg-[var(--color-panel)]">
+        <CardHeader>
+          <CardTitle className="flex items-center gap-2">
+            <Building2 size={18} className="text-primary" />
+            소속 테넌트
+          </CardTitle>
+          <CardDescription>
+            현재 이 그룹에 포함된 테넌트 목록입니다.
+          </CardDescription>
+        </CardHeader>
+        <CardContent>
+          <Table>
+            <TableHeader>
+              <TableRow>
+                <TableHead>이름</TableHead>
+                <TableHead>Slug</TableHead>
+                <TableHead className="text-right">제외</TableHead>
+              </TableRow>
+            </TableHeader>
+            <TableBody>
+              {group.tenants?.length === 0 && (
+                <TableRow>
+                  <TableCell colSpan={3} className="text-center py-8 text-muted-foreground">
+                    소속된 테넌트가 없습니다.
+                  </TableCell>
+                </TableRow>
+              )}
+              {group.tenants?.map((t) => (
+                <TableRow key={t.id}>
+                  <TableCell className="font-medium">{t.name}</TableCell>
+                  <TableCell className="text-xs">{t.slug}</TableCell>
+                  <TableCell className="text-right">
+                    <Button 
+                        variant="ghost" 
+                        size="sm" 
+                        onClick={() => handleRemoveTenant(t.id)}
+                        disabled={removeMutation.isPending}
+                    >
+                      <Trash2 size={14} className="text-destructive" />
+                    </Button>
+                  </TableCell>
+                </TableRow>
+              ))}
+            </TableBody>
+          </Table>
+        </CardContent>
+      </Card>
+
+      {/* 추가 가능한 테넌트 */}
+      <Card className="bg-[var(--color-panel)]">
+        <CardHeader>
+          <div className="flex items-center justify-between">
+            <CardTitle className="flex items-center gap-2">
+                <Plus size={18} className="text-primary" />
+                테넌트 추가
+            </CardTitle>
+            <div className="relative w-48">
+                <Search className="absolute left-2 top-2.5 h-4 w-4 text-muted-foreground" />
+                <Input 
+                    placeholder="검색..." 
+                    className="pl-8 h-9" 
+                    value={searchTerm}
+                    onChange={e => setSearchTerm(e.target.value)}
+                />
+            </div>
+          </div>
+          <CardDescription>
+            다른 그룹에 속하지 않았거나 이동이 필요한 테넌트를 선택하세요.
+          </CardDescription>
+        </CardHeader>
+        <CardContent>
+          <Table>
+            <TableHeader>
+              <TableRow>
+                <TableHead>이름</TableHead>
+                <TableHead>상태</TableHead>
+                <TableHead className="text-right">추가</TableHead>
+              </TableRow>
+            </TableHeader>
+            <TableBody>
+              {filteredAvailable.length === 0 && (
+                <TableRow>
+                  <TableCell colSpan={3} className="text-center py-8 text-muted-foreground">
+                    추가할 수 있는 테넌트가 없습니다.
+                  </TableCell>
+                </TableRow>
+              )}
+              {filteredAvailable.map((t) => (
+                <TableRow key={t.id}>
+                  <TableCell>
+                    <div className="font-medium">{t.name}</div>
+                    <div className="text-[10px] text-muted-foreground">{t.slug}</div>
+                  </TableCell>
+                  <TableCell>
+                    <Badge variant="outline" className="text-[10px]">
+                        {t.status}
+                    </Badge>
+                  </TableCell>
+                  <TableCell className="text-right">
+                    <Button 
+                        variant="outline" 
+                        size="sm" 
+                        onClick={() => handleAddTenant(t.id)}
+                        disabled={addMutation.isPending}
+                    >
+                      <Plus size={14} />
+                    </Button>
+                  </TableCell>
+                </TableRow>
+              ))}
+            </TableBody>
+          </Table>
+        </CardContent>
+      </Card>
+    </div>
+  );
+}
+
+export default TenantGroupTenantsTab;
diff --git a/adminfront/src/features/tenants/routes/TenantProfilePage.tsx b/adminfront/src/features/tenants/routes/TenantProfilePage.tsx
index f75a3f39..48fed2b0 100644
--- a/adminfront/src/features/tenants/routes/TenantProfilePage.tsx
+++ b/adminfront/src/features/tenants/routes/TenantProfilePage.tsx
@@ -18,6 +18,7 @@ import {
   approveTenant,
   deleteTenant,
   fetchTenant,
+  fetchTenantGroups,
   updateTenant,
 } from "../../../lib/adminApi";
 
@@ -35,11 +36,17 @@ export function TenantProfilePage() {
     queryFn: () => fetchTenant(tenantId),
   });
 
+  const groupsQuery = useQuery({
+    queryKey: ["tenant-groups", { limit: 100 }],
+    queryFn: () => fetchTenantGroups(100, 0),
+  });
+
   const [name, setName] = useState("");
   const [slug, setSlug] = useState("");
   const [description, setDescription] = useState("");
   const [status, setStatus] = useState("active");
   const [domains, setDomains] = useState("");
+  const [tenantGroupId, setTenantGroupId] = useState("");
 
   useEffect(() => {
     if (tenantQuery.data) {
@@ -48,6 +55,7 @@ export function TenantProfilePage() {
       setDescription(tenantQuery.data.description ?? "");
       setStatus(tenantQuery.data.status);
       setDomains(tenantQuery.data.domains?.join(", ") ?? "");
+      setTenantGroupId(tenantQuery.data.tenantGroupId ?? "");
     }
   }, [tenantQuery.data]);
 
@@ -58,6 +66,7 @@ export function TenantProfilePage() {
         slug,
         description: description || undefined,
         status,
+        tenantGroupId: tenantGroupId || undefined,
         domains: domains
           .split(",")
           .map((d) => d.trim())
@@ -136,6 +145,24 @@ export function TenantProfilePage() {
               onChange={(e) => setDescription(e.target.value)}
             />
           </div>
+          <div className="space-y-2">
+            <Label className="text-sm font-semibold">Tenant Group</Label>
+            <select
+              value={tenantGroupId}
+              onChange={(e) => setTenantGroupId(e.target.value)}
+              className="flex h-10 w-full rounded-md border border-input bg-background px-3 py-2 text-sm ring-offset-background file:border-0 file:bg-transparent file:text-sm file:font-medium placeholder:text-muted-foreground focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-offset-2 disabled:cursor-not-allowed disabled:opacity-50"
+            >
+              <option value="">그룹 없음</option>
+              {groupsQuery.data?.items.map((group) => (
+                <option key={group.id} value={group.id}>
+                  {group.name} ({group.slug})
+                </option>
+              ))}
+            </select>
+            <p className="text-xs text-muted-foreground">
+              테넌트가 속할 그룹을 지정합니다. 그룹 관리자는 소속 테넌트에 대한 접근 권한을 가집니다.
+            </p>
+          </div>
           <div className="space-y-2">
             <Label className="text-sm font-semibold">
               Allowed Domains (Comma separated)
diff --git a/adminfront/src/lib/adminApi.ts b/adminfront/src/lib/adminApi.ts
index 4f2ea618..409a504c 100644
--- a/adminfront/src/lib/adminApi.ts
+++ b/adminfront/src/lib/adminApi.ts
@@ -27,6 +27,7 @@ export type TenantSummary = {
   status: string;
   domains?: string[];
   config?: Record<string, unknown>;
+  tenantGroupId?: string;
   createdAt: string;
   updatedAt: string;
 };
@@ -38,6 +39,7 @@ export type TenantCreateRequest = {
   status?: string;
   domains?: string[];
   config?: Record<string, unknown>;
+  tenantGroupId?: string;
 };
 
 export type TenantListResponse = {
@@ -54,6 +56,7 @@ export type TenantUpdateRequest = {
   status?: string;
   domains?: string[];
   config?: Record<string, unknown>;
+  tenantGroupId?: string;
 };
 
 export type ApiKeySummary = {
@@ -139,8 +142,7 @@ export async function approveTenant(tenantId: string) {
   return data;
 }
 
-<<<<<<< HEAD
-// Group Management
+// User Group Management (Within a Tenant)
 export type GroupMember = {
   id: string;
   name: string;
@@ -165,8 +167,34 @@ export type GroupCreateRequest = {
 export async function fetchGroups(tenantId: string) {
   const { data } = await apiClient.get<GroupSummary[]>(
     `/v1/admin/tenants/${tenantId}/groups`,
-=======
-// Tenant Group Management
+  );
+  return data;
+}
+
+export async function createGroup(
+  tenantId: string,
+  payload: GroupCreateRequest,
+) {
+  const { data } = await apiClient.post<GroupSummary>(
+    `/v1/admin/tenants/${tenantId}/groups`,
+    payload,
+  );
+  return data;
+}
+
+export async function deleteGroup(groupId: string) {
+  await apiClient.delete(`/v1/admin/groups/${groupId}`);
+}
+
+export async function addGroupMember(groupId: string, userId: string) {
+  await apiClient.post(`/v1/admin/groups/${groupId}/members`, { userId });
+}
+
+export async function removeGroupMember(groupId: string, userId: string) {
+  await apiClient.delete(`/v1/admin/groups/${groupId}/members/${userId}`);
+}
+
+// Tenant Group Management (Global Grouping of Tenants)
 export type TenantGroupSummary = {
   id: string;
   name: string;
@@ -191,19 +219,10 @@ export async function fetchTenantGroups(limit = 50, offset = 0) {
     {
       params: { limit, offset },
     },
->>>>>>> d7d2e16 (feat: 테넌트 그룹(Tenant Group) 기능 구현 #239)
   );
   return data;
 }
 
-<<<<<<< HEAD
-export async function createGroup(
-  tenantId: string,
-  payload: GroupCreateRequest,
-) {
-  const { data } = await apiClient.post<GroupSummary>(
-    `/v1/admin/tenants/${tenantId}/groups`,
-=======
 export async function fetchTenantGroup(id: string) {
   const { data } = await apiClient.get<TenantGroupSummary>(
     `/v1/admin/tenant-groups/${id}`,
@@ -218,24 +237,11 @@ export async function createTenantGroup(payload: {
 }) {
   const { data } = await apiClient.post<TenantGroupSummary>(
     "/v1/admin/tenant-groups",
->>>>>>> d7d2e16 (feat: 테넌트 그룹(Tenant Group) 기능 구현 #239)
     payload,
   );
   return data;
 }
 
-<<<<<<< HEAD
-export async function deleteGroup(groupId: string) {
-  await apiClient.delete(`/v1/admin/groups/${groupId}`);
-}
-
-export async function addGroupMember(groupId: string, userId: string) {
-  await apiClient.post(`/v1/admin/groups/${groupId}/members`, { userId });
-}
-
-export async function removeGroupMember(groupId: string, userId: string) {
-  await apiClient.delete(`/v1/admin/groups/${groupId}/members/${userId}`);
-=======
 export async function updateTenantGroup(
   id: string,
   payload: { name: string; description?: string },
@@ -259,7 +265,6 @@ export async function removeTenantFromGroup(groupId: string, tenantId: string) {
   await apiClient.delete(
     `/v1/admin/tenant-groups/${groupId}/tenants/${tenantId}`,
   );
->>>>>>> d7d2e16 (feat: 테넌트 그룹(Tenant Group) 기능 구현 #239)
 }
 
 // API Key Management (M2M)
@@ -441,4 +446,4 @@ export async function updateRelyingParty(id: string, payload: HydraClientReq) {
 
 export async function deleteRelyingParty(id: string) {
   await apiClient.delete(`/v1/admin/relying-parties/${id}`);
-}
+}
\ No newline at end of file
diff --git a/backend/cmd/server/main.go b/backend/cmd/server/main.go
index bf137078..6f4f1ecf 100644
--- a/backend/cmd/server/main.go
+++ b/backend/cmd/server/main.go
@@ -260,7 +260,7 @@ func main() {
 	authHandler := handler.NewAuthHandler(redisService, idpProvider, auditRepo, oathkeeperRepo, tenantService, ketoService, userRepo, consentRepo)
 	adminHandler := handler.NewAdminHandler()
 	devHandler := handler.NewDevHandler(redisService, secretRepo, consentRepo)
-	tenantHandler := handler.NewTenantHandler(db, tenantService)
+	tenantHandler := handler.NewTenantHandler(db, tenantService, ketoService)
 	tenantGroupHandler := handler.NewTenantGroupHandler(tenantGroupService)
 	relyingPartyHandler := handler.NewRelyingPartyHandler(relyingPartyService)
 	kratosAdminService := service.NewKratosAdminService()
diff --git a/backend/internal/handler/tenant_handler.go b/backend/internal/handler/tenant_handler.go
index 53d858bb..db7164be 100644
--- a/backend/internal/handler/tenant_handler.go
+++ b/backend/internal/handler/tenant_handler.go
@@ -14,22 +14,24 @@ import (
 type TenantHandler struct {
 	DB      *gorm.DB
 	Service service.TenantService
+	Keto    service.KetoService
 }
 
-func NewTenantHandler(db *gorm.DB, svc service.TenantService) *TenantHandler {
-	return &TenantHandler{DB: db, Service: svc}
+func NewTenantHandler(db *gorm.DB, svc service.TenantService, keto service.KetoService) *TenantHandler {
+	return &TenantHandler{DB: db, Service: svc, Keto: keto}
 }
 
 type tenantSummary struct {
-	ID          string         `json:"id"`
-	Name        string         `json:"name"`
-	Slug        string         `json:"slug"`
-	Description string         `json:"description"`
-	Status      string         `json:"status"`
-	Domains     []string       `json:"domains,omitempty"`
-	Config      domain.JSONMap `json:"config,omitempty"`
-	CreatedAt   string         `json:"createdAt"`
-	UpdatedAt   string         `json:"updatedAt"`
+	ID            string         `json:"id"`
+	Name          string         `json:"name"`
+	Slug          string         `json:"slug"`
+	Description   string         `json:"description"`
+	Status        string         `json:"status"`
+	TenantGroupID *string        `json:"tenantGroupId,omitempty"`
+	Domains       []string       `json:"domains,omitempty"`
+	Config        domain.JSONMap `json:"config,omitempty"`
+	CreatedAt     string         `json:"createdAt"`
+	UpdatedAt     string         `json:"updatedAt"`
 }
 
 type tenantListResponse struct {
@@ -123,7 +125,7 @@ func (h *TenantHandler) GetTenant(c *fiber.Ctx) error {
 	}
 
 	var tenant domain.Tenant
-	if err := h.DB.Preload("Domains").First(&tenant, "id = ?", tenantID).Error; err != nil {
+	if err := h.DB.Preload("Domains").Preload("TenantGroup").First(&tenant, "id = ?", tenantID).Error; err != nil {
 		if errors.Is(err, gorm.ErrRecordNotFound) {
 			return c.Status(fiber.StatusNotFound).JSON(fiber.Map{"error": "tenant not found"})
 		}
@@ -204,12 +206,13 @@ func (h *TenantHandler) UpdateTenant(c *fiber.Ctx) error {
 	}
 
 	var req struct {
-		Name        *string        `json:"name"`
-		Slug        *string        `json:"slug"`
-		Description *string        `json:"description"`
-		Status      *string        `json:"status"`
-		Domains     []string       `json:"domains"`
-		Config      map[string]any `json:"config"`
+		Name          *string        `json:"name"`
+		Slug          *string        `json:"slug"`
+		Description   *string        `json:"description"`
+		Status        *string        `json:"status"`
+		TenantGroupID *string        `json:"tenantGroupId"`
+		Domains       []string       `json:"domains"`
+		Config        map[string]any `json:"config"`
 	}
 	if err := c.BodyParser(&req); err != nil {
 		return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{"error": "invalid request body"})
@@ -251,6 +254,29 @@ func (h *TenantHandler) UpdateTenant(c *fiber.Ctx) error {
 		tenant.Config = req.Config
 	}
 
+	// Handle Group Change
+	if req.TenantGroupID != nil {
+		oldGroupID := tenant.TenantGroupID
+		newGroupID := req.TenantGroupID
+		if *newGroupID == "" {
+			newGroupID = nil
+		}
+
+		// Update Keto if group changed
+		if h.Keto != nil {
+			// Remove old group relation if existed
+			if oldGroupID != nil && (newGroupID == nil || *oldGroupID != *newGroupID) {
+				_ = h.Keto.DeleteRelation(c.Context(), "Tenant", tenant.ID, "parent_group", *oldGroupID)
+			}
+			// Add new group relation
+			if newGroupID != nil && (oldGroupID == nil || *oldGroupID != *newGroupID) {
+				_ = h.Keto.CreateRelation(c.Context(), "Tenant", tenant.ID, "parent_group", *newGroupID)
+			}
+		}
+
+		tenant.TenantGroupID = newGroupID
+	}
+
 	if err := h.DB.Save(&tenant).Error; err != nil {
 		return c.Status(fiber.StatusInternalServerError).JSON(fiber.Map{"error": err.Error()})
 	}
@@ -308,15 +334,16 @@ func mapTenantSummary(t domain.Tenant) tenantSummary {
 	}
 
 	return tenantSummary{
-		ID:          t.ID,
-		Name:        t.Name,
-		Slug:        t.Slug,
-		Description: t.Description,
-		Status:      t.Status,
-		Domains:     domains,
-		Config:      t.Config,
-		CreatedAt:   t.CreatedAt.Format(time.RFC3339),
-		UpdatedAt:   t.UpdatedAt.Format(time.RFC3339),
+		ID:            t.ID,
+		Name:          t.Name,
+		Slug:          t.Slug,
+		Description:   t.Description,
+		Status:        t.Status,
+		TenantGroupID: t.TenantGroupID,
+		Domains:       domains,
+		Config:        t.Config,
+		CreatedAt:     t.CreatedAt.Format(time.RFC3339),
+		UpdatedAt:     t.UpdatedAt.Format(time.RFC3339),
 	}
 }