diff --git a/src/components/common/Header.tsx b/src/components/common/Header.tsx
index 441d34c7..63782aee 100644
--- a/src/components/common/Header.tsx
+++ b/src/components/common/Header.tsx
@@ -7,7 +7,7 @@ import { logout } from '@services/authService';
 import useToast from '@hooks/useToast';
 
 export default function Header() {
-  const { userInfo: userInfoData, onLogout, clearUserInfo } = useStore();
+  const { userInfo: userInfoData, onLogout, clearUserInfo, isAuthenticated } = useStore();
   const navigate = useNavigate();
   const { toastSuccess } = useToast();
 
@@ -33,7 +33,9 @@ export default function Header() {
         </Link>
       </div>
       <nav className="flex items-center">
-        <div className="tracking-tight text-white">{userInfoData.nickname}님의 Grow Up! 응원합니다.</div>
+        {isAuthenticated && (
+          <div className="tracking-tight text-white">{userInfoData.nickname}님의 Grow Up! 응원합니다.</div>
+        )}
         <NavLink to="/" className="ml-10 hover:brightness-90">
           {({ isActive }) => <FiHome className={`size-20 ${isActive ? 'text-selected' : 'text-white'}`} />}
         </NavLink>
@@ -43,9 +45,9 @@ export default function Header() {
         <button
           type="button"
           className="ml-10 h-20 rounded-md bg-white px-4 tracking-tight hover:brightness-90"
-          onClick={handleLogout}
+          onClick={isAuthenticated ? handleLogout : () => navigate('/signin')}
         >
-          Logout
+          {isAuthenticated ? 'Logout' : 'Login'}
         </button>
       </nav>
     </header>
diff --git a/src/mocks/services/authServiceHandler.ts b/src/mocks/services/authServiceHandler.ts
index eba1bea5..73f10265 100644
--- a/src/mocks/services/authServiceHandler.ts
+++ b/src/mocks/services/authServiceHandler.ts
@@ -278,16 +278,9 @@ const authServiceHandler = [
 
   // 로그아웃 API
   http.post(`${BASE_URL}/user/logout`, async ({ cookies }) => {
-    const { refreshToken, refreshTokenExpiresAt } = cookies;
+    const { refreshToken } = cookies;
     const currentTime = Date.now();
 
-    if (!refreshToken || !refreshTokenExpiresAt) {
-      return HttpResponse.json(
-        { message: '리프레시 토큰이 유효하지 않습니다. 다시 로그인해 주세요.' },
-        { status: 401 },
-      );
-    }
-
     return new HttpResponse(null, {
       status: 200,
       headers: {