diff --git a/src/app/(main)/layout.tsx b/src/app/(main)/layout.tsx
index 04c5474..3f9bda4 100644
--- a/src/app/(main)/layout.tsx
+++ b/src/app/(main)/layout.tsx
@@ -3,43 +3,51 @@
 import { useEffect } from "react";
 import { useRouter } from "next/navigation";
 import { useAuthStore } from "@/store/auth-store";
+import { useMenuStore } from "@/store/menu-store";
 import { Sidebar } from "@/components/layout/sidebar";
 import { Header } from "@/components/layout/header";
 import { Loading } from "@/components/ui/loading";
 
-// mainFS.jsp 대응 - 프레임셋 → Sidebar + Header + Content 레이아웃
 export default function MainLayout({ children }: { children: React.ReactNode }) {
   const router = useRouter();
   const { user, isLoading, fetchUser } = useAuthStore();
+  const { mobileOpen, setMobileOpen } = useMenuStore();
+
+  useEffect(() => { fetchUser(); }, [fetchUser]);
 
   useEffect(() => {
-    fetchUser();
-  }, [fetchUser]);
-
-  useEffect(() => {
-    if (!isLoading && !user) {
-      router.push("/login");
-    }
+    if (!isLoading && !user) router.push("/login");
   }, [isLoading, user, router]);
 
-  if (isLoading) {
-    return <Loading message="로딩 중..." />;
-  }
-
+  if (isLoading) return <Loading message="로딩 중..." />;
   if (!user) return null;
 
   return (
     <div className="flex h-screen overflow-hidden">
-      {/* 사이드바 (menu.jsp 대응) */}
-      <Sidebar />
+      {/* 사이드바 — 데스크탑은 정상, 모바일은 오버레이로 등장 */}
+      <div
+        className={
+          "fixed inset-y-0 left-0 z-50 shadow-2xl transition-transform duration-200 " +
+          "lg:static lg:shadow-none lg:translate-x-0 " +
+          (mobileOpen ? "translate-x-0" : "-translate-x-full lg:translate-x-0")
+        }
+      >
+        <Sidebar />
+      </div>
+
+      {/* 모바일 오버레이 배경 — 사이드바 펼쳤을 때 어둡게 */}
+      {mobileOpen && (
+        <button
+          aria-label="사이드바 닫기"
+          onClick={() => setMobileOpen(false)}
+          className="fixed inset-0 bg-slate-900/40 z-40 lg:hidden"
+        />
+      )}
 
       {/* 메인 영역 */}
       <div className="flex-1 flex flex-col overflow-hidden">
-        {/* 헤더 (header.jsp 대응) */}
         <Header />
-
-        {/* 콘텐츠 (contents_page iframe 대응) */}
-        <main className="flex-1 overflow-hidden p-4 flex flex-col min-h-0">
+        <main className="flex-1 overflow-auto p-3 sm:p-4 flex flex-col min-h-0">
           {children}
         </main>
       </div>
diff --git a/src/components/layout/header.tsx b/src/components/layout/header.tsx
index 59b035f..a240d67 100644
--- a/src/components/layout/header.tsx
+++ b/src/components/layout/header.tsx
@@ -3,11 +3,11 @@
 import { useEffect } from "react";
 import { useAuthStore } from "@/store/auth-store";
 import { useMenuStore } from "@/store/menu-store";
-import { LogOut, User, BookOpen } from "lucide-react";
+import { LogOut, User, BookOpen, Menu as MenuIcon } from "lucide-react";
 
 export function Header() {
   const { user, logout } = useAuthStore();
-  const { topMenus, activeTopMenu, fetchTopMenus, fetchSideMenus } = useMenuStore();
+  const { topMenus, activeTopMenu, fetchTopMenus, fetchSideMenus, setMobileOpen } = useMenuStore();
 
   useEffect(() => {
     fetchTopMenus();
@@ -25,7 +25,16 @@ export function Header() {
 
   return (
     <header className="h-12 bg-white border-b border-gray-200 flex items-center px-3 sm:px-4 shrink-0 gap-2">
-      {/* 좌측 여백만 — 모바일에서 사이드바 토글이 이 영역을 차지함 */}
+      {/* 모바일 햄버거 — lg 이상에서는 숨김 */}
+      <button
+        onClick={() => setMobileOpen(true)}
+        className="lg:hidden p-1.5 -ml-1 text-gray-600 hover:text-emerald-700 rounded"
+        aria-label="메뉴 열기"
+      >
+        <MenuIcon size={20} />
+      </button>
+
+      {/* 좌측 여백 */}
       <div className="flex-1" />
 
       {/* 매뉴얼 보기 (새 탭) */}
@@ -43,12 +52,13 @@ export function Header() {
       {/* 우측: 사용자명(프로필 링크) + 로그아웃 */}
       <a
         href="/profile"
-        className="flex items-center gap-1.5 text-xs sm:text-sm text-gray-600 hover:text-emerald-700 hover:underline pl-2 border-l border-gray-200"
+        className="flex items-center gap-1.5 text-xs sm:text-sm text-gray-600 hover:text-emerald-700 hover:underline pl-2 border-l border-gray-200 min-w-0"
         title="회원정보 수정"
       >
-        <User size={14} className="text-gray-400" />
-        <span className="truncate max-w-[200px]">
-          {user?.userName} {user?.deptName ? `(${user.deptName})` : ""}
+        <User size={14} className="text-gray-400 shrink-0" />
+        <span className="truncate max-w-[110px] sm:max-w-[200px]">
+          {user?.userName}
+          <span className="hidden sm:inline">{user?.deptName ? ` (${user.deptName})` : ""}</span>
         </span>
       </a>
 
diff --git a/src/components/layout/sidebar.tsx b/src/components/layout/sidebar.tsx
index dbf5577..2a0556b 100644
--- a/src/components/layout/sidebar.tsx
+++ b/src/components/layout/sidebar.tsx
@@ -11,7 +11,7 @@ import {
   ShoppingCart, FileText, Warehouse, Boxes, Factory, Wrench,
   Headset, Clock, Calculator, Coins, Truck, Settings,
   ClipboardCheck, Compass, GitBranch, Puzzle, Stamp, Folder,
-  ChevronDown, Menu as MenuIcon,
+  ChevronDown, Menu as MenuIcon, X,
 } from "lucide-react";
 
 const ICON_COMPONENTS: Record<string, React.ElementType> = {
@@ -34,7 +34,7 @@ export function Sidebar() {
   const router = useRouter();
   const {
     sideMenus, activeSubMenu, isCollapsed,
-    setActiveSubMenu, toggleCollapsed,
+    setActiveSubMenu, toggleCollapsed, setMobileOpen,
   } = useMenuStore();
   const [openCategories, setOpenCategories] = useState<Set<string>>(new Set());
   // 축소 모드 호버 팝업
@@ -61,6 +61,7 @@ export function Sidebar() {
   const handleSubMenuClick = (menuObjId: string, menuUrl: string) => {
     setActiveSubMenu(menuObjId);
     setHoveredCategory(null); // 팝업 닫기
+    setMobileOpen(false);     // 모바일에서 메뉴 선택 시 자동 닫기
     const path = mapMenuUrl(menuUrl);
     if (path) router.push(path);
   };
@@ -120,9 +121,18 @@ export function Sidebar() {
         ) : (
           <img src="/momo-icon.svg" alt="MOMO" width={24} height={24} className="mx-auto" />
         )}
+        {/* 모바일: X로 닫기, 데스크탑: 햄버거로 축소/확장 */}
+        <button
+          onClick={() => setMobileOpen(false)}
+          className="lg:hidden text-[#8890a0] hover:text-white hover:bg-white/[0.08] rounded p-1 transition-colors shrink-0"
+          aria-label="메뉴 닫기"
+        >
+          <X size={18} />
+        </button>
         <button
           onClick={toggleCollapsed}
-          className="text-[#8890a0] hover:text-white hover:bg-white/[0.08] rounded p-1 transition-colors shrink-0"
+          className="hidden lg:flex text-[#8890a0] hover:text-white hover:bg-white/[0.08] rounded p-1 transition-colors shrink-0"
+          aria-label="사이드바 축소/확장"
         >
           <MenuIcon size={16} />
         </button>
diff --git a/src/store/menu-store.ts b/src/store/menu-store.ts
index 36a5be7..b6e4ba9 100644
--- a/src/store/menu-store.ts
+++ b/src/store/menu-store.ts
@@ -7,11 +7,14 @@ interface MenuState {
   activeTopMenu: string;
   activeSubMenu: string;
   isCollapsed: boolean;
+  /** 모바일에서 사이드바 오버레이로 펼침 여부 */
+  mobileOpen: boolean;
   setTopMenus: (menus: { OBJID: string; MENU_NAME_KOR: string }[]) => void;
   setSideMenus: (menus: MenuItem[]) => void;
   setActiveTopMenu: (id: string) => void;
   setActiveSubMenu: (id: string) => void;
   toggleCollapsed: () => void;
+  setMobileOpen: (v: boolean) => void;
   fetchTopMenus: () => Promise<void>;
   fetchSideMenus: (menuObjId: string) => Promise<void>;
 }
@@ -22,12 +25,14 @@ export const useMenuStore = create<MenuState>((set) => ({
   activeTopMenu: "",
   activeSubMenu: "",
   isCollapsed: false,
+  mobileOpen: false,
 
   setTopMenus: (topMenus) => set({ topMenus }),
   setSideMenus: (sideMenus) => set({ sideMenus }),
   setActiveTopMenu: (activeTopMenu) => set({ activeTopMenu }),
   setActiveSubMenu: (activeSubMenu) => set({ activeSubMenu }),
   toggleCollapsed: () => set((s) => ({ isCollapsed: !s.isCollapsed })),
+  setMobileOpen: (v) => set({ mobileOpen: v }),
 
   fetchTopMenus: async () => {
     const res = await fetch("/api/menu/top");