diff --git a/frontend/components/layout/AppLayout.tsx b/frontend/components/layout/AppLayout.tsx
index 959ba363..7f365d29 100644
--- a/frontend/components/layout/AppLayout.tsx
+++ b/frontend/components/layout/AppLayout.tsx
@@ -215,8 +215,8 @@ function AppLayoutInner({ children }: AppLayoutProps) {
     };
 
     checkIsMobile();
-    window.addEventListener('resize', checkIsMobile);
-    return () => window.removeEventListener('resize', checkIsMobile);
+    window.addEventListener("resize", checkIsMobile);
+    return () => window.removeEventListener("resize", checkIsMobile);
   }, []);
 
   // 프로필 관련 로직
@@ -322,18 +322,20 @@ function AppLayoutInner({ children }: AppLayoutProps) {
     return (
       <div key={menu.id}>
         <div
-          className={`group flex cursor-pointer items-center justify-between rounded-lg px-3 py-2 text-sm font-medium transition-colors duration-200 ease-in-out h-10 ${
+          className={`group flex h-10 cursor-pointer items-center justify-between rounded-lg px-3 py-2 text-sm font-medium transition-colors duration-200 ease-in-out ${
             pathname === menu.url
-              ? "bg-gradient-to-br from-slate-100 to-blue-100/40 text-slate-900 border-l-4 border-blue-500"
+              ? "border-l-4 border-blue-500 bg-gradient-to-br from-slate-100 to-blue-100/40 text-slate-900"
               : isExpanded
                 ? "bg-slate-100 text-slate-900"
                 : "text-slate-600 hover:bg-slate-50 hover:text-slate-900"
           } ${level > 0 ? "ml-6" : ""}`}
           onClick={() => handleMenuClick(menu)}
         >
-          <div className="flex items-center min-w-0 flex-1">
+          <div className="flex min-w-0 flex-1 items-center">
             {menu.icon}
-            <span className="ml-3 truncate" title={menu.name}>{menu.name}</span>
+            <span className="ml-3 truncate" title={menu.name}>
+              {menu.name}
+            </span>
           </div>
           {menu.hasChildren && (
             <div className="ml-auto">
@@ -350,14 +352,16 @@ function AppLayoutInner({ children }: AppLayoutProps) {
                 key={child.id}
                 className={`flex cursor-pointer items-center rounded-lg px-3 py-2 text-sm transition-colors hover:cursor-pointer ${
                   pathname === child.url
-                    ? "bg-gradient-to-br from-slate-100 to-blue-100/40 text-slate-900 border-l-4 border-blue-500"
+                    ? "border-l-4 border-blue-500 bg-gradient-to-br from-slate-100 to-blue-100/40 text-slate-900"
                     : "text-slate-600 hover:bg-slate-50 hover:text-slate-900"
                 }`}
                 onClick={() => handleMenuClick(child)}
               >
-                <div className="flex items-center min-w-0 flex-1">
+                <div className="flex min-w-0 flex-1 items-center">
                   {child.icon}
-                  <span className="ml-3 truncate" title={child.name}>{child.name}</span>
+                  <span className="ml-3 truncate" title={child.name}>
+                    {child.name}
+                  </span>
                 </div>
               </div>
             ))}
@@ -406,10 +410,10 @@ function AppLayoutInner({ children }: AppLayoutProps) {
         {/* 왼쪽 사이드바 */}
         <aside
           className={`${
-            isMobile 
+            isMobile
               ? (sidebarOpen ? "translate-x-0" : "-translate-x-full") + " fixed top-14 left-0 z-40"
-              : "translate-x-0 relative top-0 z-auto"
-          } flex h-full w-72 min-w-72 max-w-72 flex-col border-r border-slate-200 bg-white transition-transform duration-300`}
+              : "relative top-0 z-auto translate-x-0"
+          } flex h-full w-72 max-w-72 min-w-72 flex-col border-r border-slate-200 bg-white transition-transform duration-300`}
         >
           {/* 사이드바 상단 - Admin/User 모드 전환 버튼 (관리자만) */}
           {(user as ExtendedUserInfo)?.userType === "admin" && (
@@ -453,7 +457,7 @@ function AppLayoutInner({ children }: AppLayoutProps) {
         </aside>
 
         {/* 가운데 컨텐츠 영역 - overflow 문제 해결 */}
-        <main className="flex-1 min-w-0 bg-white overflow-auto">{children}</main>
+        <main className="min-w-0 flex-1 overflow-auto bg-white">{children}</main>
       </div>
 
       {/* 프로필 수정 모달 */}
@@ -461,7 +465,7 @@ function AppLayoutInner({ children }: AppLayoutProps) {
         isOpen={isModalOpen}
         user={user}
         formData={formData}
-        selectedImage={selectedImage}
+        selectedImage={selectedImage || ""}
         isSaving={isSaving}
         departments={departments}
         alertModal={alertModal}
diff --git a/frontend/components/layout/ProfileModal.tsx b/frontend/components/layout/ProfileModal.tsx
index d2467bac..b50eb657 100644
--- a/frontend/components/layout/ProfileModal.tsx
+++ b/frontend/components/layout/ProfileModal.tsx
@@ -101,17 +101,21 @@ export function ProfileModal({
             {/* 프로필 사진 섹션 */}
             <div className="flex flex-col items-center space-y-4">
               <div className="relative">
-                <Avatar className="h-24 w-24">
-                  {selectedImage ? (
-                    <AvatarImage src={selectedImage} alt="프로필 사진 미리보기" />
-                  ) : user?.photo ? (
-                    <AvatarImage src={user.photo} alt="기존 프로필 사진" />
+                <div className="relative flex h-24 w-24 shrink-0 overflow-hidden rounded-full">
+                  {selectedImage && selectedImage.trim() !== "" ? (
+                    <img
+                      src={selectedImage}
+                      alt="프로필 사진 미리보기"
+                      className="aspect-square h-full w-full object-cover"
+                    />
                   ) : (
-                    <AvatarFallback className="text-lg">{formData.userName?.substring(0, 1) || "U"}</AvatarFallback>
+                    <div className="flex h-full w-full items-center justify-center rounded-full bg-slate-200 text-2xl font-semibold text-slate-700">
+                      {formData.userName?.substring(0, 1)?.toUpperCase() || "U"}
+                    </div>
                   )}
-                </Avatar>
+                </div>
 
-                {(selectedImage || user?.photo) && (
+                {selectedImage && selectedImage.trim() !== "" ? (
                   <Button
                     type="button"
                     variant="destructive"
@@ -121,7 +125,7 @@ export function ProfileModal({
                   >
                     <X className="h-3 w-3" />
                   </Button>
-                )}
+                ) : null}
               </div>
 
               <div className="flex gap-2">
diff --git a/frontend/components/layout/UserDropdown.tsx b/frontend/components/layout/UserDropdown.tsx
index 386a4334..4ce4ef01 100644
--- a/frontend/components/layout/UserDropdown.tsx
+++ b/frontend/components/layout/UserDropdown.tsx
@@ -26,20 +26,38 @@ export function UserDropdown({ user, onProfileClick, onLogout }: UserDropdownPro
     <DropdownMenu modal={false}>
       <DropdownMenuTrigger asChild>
         <Button variant="ghost" className="relative h-8 w-8 rounded-full">
-          <Avatar className="h-8 w-8">
-            {user.photo ? <AvatarImage src={user.photo} alt={user.userName || "User"} /> : null}
-            <AvatarFallback>{user.userName?.substring(0, 1) || "U"}</AvatarFallback>
-          </Avatar>
+          <div className="relative flex h-8 w-8 shrink-0 overflow-hidden rounded-full">
+            {user.photo && user.photo.trim() !== "" && user.photo !== "null" ? (
+              <img
+                src={user.photo}
+                alt={user.userName || "User"}
+                className="aspect-square h-full w-full object-cover"
+              />
+            ) : (
+              <div className="flex h-full w-full items-center justify-center rounded-full bg-slate-200 font-semibold text-slate-700">
+                {user.userName?.substring(0, 1)?.toUpperCase() || "U"}
+              </div>
+            )}
+          </div>
         </Button>
       </DropdownMenuTrigger>
       <DropdownMenuContent className="w-56" align="end">
         <DropdownMenuLabel className="font-normal">
           <div className="flex items-center space-x-3">
             {/* 프로필 사진 표시 */}
-            <Avatar className="h-12 w-12">
-              {user.photo ? <AvatarImage src={user.photo} alt={user.userName || "User"} /> : null}
-              <AvatarFallback>{user.userName?.substring(0, 1) || "U"}</AvatarFallback>
-            </Avatar>
+            <div className="relative flex h-12 w-12 shrink-0 overflow-hidden rounded-full">
+              {user.photo && user.photo.trim() !== "" && user.photo !== "null" ? (
+                <img
+                  src={user.photo}
+                  alt={user.userName || "User"}
+                  className="aspect-square h-full w-full object-cover"
+                />
+              ) : (
+                <div className="flex h-full w-full items-center justify-center rounded-full bg-slate-200 text-base font-semibold text-slate-700">
+                  {user.userName?.substring(0, 1)?.toUpperCase() || "U"}
+                </div>
+              )}
+            </div>
 
             {/* 사용자 정보 */}
             <div className="flex flex-col space-y-1">
diff --git a/frontend/constants/layout.ts b/frontend/constants/layout.ts
index 73b9eb22..b447e9f4 100644
--- a/frontend/constants/layout.ts
+++ b/frontend/constants/layout.ts
@@ -29,6 +29,9 @@ export const MESSAGES = {
   CONFIRM: "정말로 진행하시겠습니까?",
   NO_DATA: "데이터가 없습니다.",
   NO_MENUS: "사용 가능한 메뉴가 없습니다.",
+  FILE_SIZE_ERROR: "파일 크기가 너무 큽니다. 5MB 이하의 파일을 선택해주세요.",
+  FILE_TYPE_ERROR: "이미지 파일만 업로드 가능합니다.",
+  PROFILE_SAVE_ERROR: "프로필 저장 중 오류가 발생했습니다.",
 } as const;
 
 export const MENU_ICONS = {
diff --git a/frontend/hooks/useProfile.ts b/frontend/hooks/useProfile.ts
index 882c0293..0498eb13 100644
--- a/frontend/hooks/useProfile.ts
+++ b/frontend/hooks/useProfile.ts
@@ -27,7 +27,7 @@ export const useProfile = (user: any, refreshUserData: () => Promise<void>, refr
       positionName: "",
       locale: "",
     },
-    selectedImage: "",
+    selectedImage: null,
     selectedFile: null,
     isSaving: false,
   });
@@ -80,13 +80,6 @@ export const useProfile = (user: any, refreshUserData: () => Promise<void>, refr
    */
   const openProfileModal = useCallback(() => {
     if (user) {
-      console.log("🔍 프로필 모달 열기 - 사용자 정보:", {
-        userName: user.userName,
-        email: user.email,
-        deptName: user.deptName,
-        locale: user.locale,
-      });
-
       // 부서 목록 로드
       loadDepartments();
 
@@ -100,7 +93,7 @@ export const useProfile = (user: any, refreshUserData: () => Promise<void>, refr
           positionName: user.positionName || "",
           locale: user.locale || "KR", // 기본값을 KR로 설정
         },
-        selectedImage: user.photo || "",
+        selectedImage: user.photo || null,
         selectedFile: null,
         isSaving: false,
       }));
@@ -113,6 +106,8 @@ export const useProfile = (user: any, refreshUserData: () => Promise<void>, refr
   const closeProfileModal = useCallback(() => {
     setModalState((prev) => ({
       ...prev,
+      selectedImage: null,
+      selectedFile: null,
       isOpen: false,
     }));
   }, []);
@@ -173,17 +168,21 @@ export const useProfile = (user: any, refreshUserData: () => Promise<void>, refr
    * 이미지 삭제
    */
   const removeImage = useCallback(() => {
-    setModalState((prev) => ({
-      ...prev,
-      selectedImage: "",
-      selectedFile: null,
-    }));
-
     // 파일 input 초기화
     const fileInput = document.getElementById("profile-image-input") as HTMLInputElement;
     if (fileInput) {
       fileInput.value = "";
     }
+
+    // 상태 업데이트 - 명시적으로 null로 설정하여 AvatarFallback이 확실히 표시되도록 함
+    setModalState((prev) => {
+      const newState = {
+        ...prev,
+        selectedImage: null, // 빈 문자열 대신 null로 설정
+        selectedFile: null,
+      };
+      return newState;
+    });
   }, []);
 
   /**
@@ -195,8 +194,8 @@ export const useProfile = (user: any, refreshUserData: () => Promise<void>, refr
     setModalState((prev) => ({ ...prev, isSaving: true }));
 
     try {
-      // 선택된 이미지가 있으면 Base64로 변환, 없으면 기존 이미지 유지
-      let photoData = user.photo || "";
+      // 이미지 데이터 결정 로직
+      let photoData: string | null | undefined = undefined;
 
       if (modalState.selectedFile) {
         // 새로 선택된 파일을 Base64로 변환
@@ -207,26 +206,29 @@ export const useProfile = (user: any, refreshUserData: () => Promise<void>, refr
           };
           reader.readAsDataURL(modalState.selectedFile!);
         });
+      } else if (modalState.selectedImage === null || modalState.selectedImage === "") {
+        // 이미지가 명시적으로 삭제된 경우 (X 버튼 클릭)
+        photoData = null;
       } else if (modalState.selectedImage && modalState.selectedImage !== user.photo) {
-        // 미리보기 이미지가 변경된 경우 사용
+        // 미리보기 이미지가 변경된 경우
         photoData = modalState.selectedImage;
       }
 
       // 사용자 정보 저장 데이터 준비
-      const updateData = {
+      const updateData: any = {
         userName: modalState.formData.userName,
         email: modalState.formData.email,
         locale: modalState.formData.locale,
-        photo: photoData !== user.photo ? photoData : undefined, // 변경된 경우만 전송
       };
 
-      console.log("프로필 업데이트 요청:", updateData);
+      // photo가 변경된 경우에만 추가 (undefined가 아닌 경우)
+      if (photoData !== undefined) {
+        updateData.photo = photoData;
+      }
 
       // API 호출 (JWT 토큰 자동 포함)
       const response = await apiCall("PUT", "/admin/profile", updateData);
 
-      console.log("프로필 업데이트 응답:", response);
-
       if (response.success || (response as any).result) {
         // locale이 변경된 경우 전역 변수와 localStorage 업데이트
         const localeChanged = modalState.formData.locale && modalState.formData.locale !== user.locale;
@@ -234,7 +236,6 @@ export const useProfile = (user: any, refreshUserData: () => Promise<void>, refr
           // 🎯 useMultiLang의 콜백 시스템을 사용하여 모든 컴포넌트에 즉시 알림
           const { notifyLanguageChange } = await import("@/hooks/useMultiLang");
           notifyLanguageChange(modalState.formData.locale);
-          console.log("🌍 사용자 locale 업데이트 (콜백 방식):", modalState.formData.locale);
         }
 
         // 성공: 사용자 정보 새로고침
@@ -242,15 +243,17 @@ export const useProfile = (user: any, refreshUserData: () => Promise<void>, refr
 
         // locale이 변경된 경우 메뉴도 새로고침
         if (localeChanged && refreshMenus) {
-          console.log("🔄 locale 변경으로 인한 메뉴 새로고침 시작");
           await refreshMenus();
-          console.log("✅ 메뉴 새로고침 완료");
         }
+
+        // 모달 상태 초기화 (저장 후 즉시 반영을 위해)
         setModalState((prev) => ({
           ...prev,
           selectedFile: null,
+          selectedImage: null,
           isOpen: false,
         }));
+
         showAlert("저장 완료", "프로필이 성공적으로 업데이트되었습니다.", "success");
       } else {
         throw new Error((response as any).message || "프로필 업데이트 실패");
diff --git a/frontend/types/profile.ts b/frontend/types/profile.ts
index 1ab60e34..57816a0c 100644
--- a/frontend/types/profile.ts
+++ b/frontend/types/profile.ts
@@ -13,7 +13,7 @@ export interface ProfileFormData {
 export interface ProfileModalState {
   isOpen: boolean;
   formData: ProfileFormData;
-  selectedImage: string;
+  selectedImage: string | null;
   selectedFile: File | null;
   isSaving: boolean;
 }