diff --git a/src/stores/login.ts b/src/stores/login.ts
index dbd1ee6..1a5cef8 100644
--- a/src/stores/login.ts
+++ b/src/stores/login.ts
@@ -61,6 +61,11 @@ export default defineStore('loginStore', {
      */
     async refreshToken() {
       const api = '/api/oauth/token';
+      const config = {
+        headers: {
+          'Content-Type':'application/x-www-form-urlencoded',
+        },
+      };
 
       this.auth.grant_type = 'refresh_token';
       this.auth.refresh_token = getCookie("luciaRefreshToken");
@@ -70,15 +75,16 @@ export default defineStore('loginStore', {
         if(response.status === 200) {
           const newAccessToken = response.data.access_token;
           const newRefreshToken = response.data.refresh_token;
-  
+
           document.cookie = `luciaToken=${newAccessToken}`;
-          document.cookie = `luciaRefreshToken=${newRefreshToken};expires=${this.expired}`;
-  
-          defaults.headers.common['Authorization'] = `Bearer ${newAccessToken}`;
-        }        
+          document.cookie = `luciaRefreshToken=${newRefreshToken};expires=${new Date(this.expired)}`;
+
+          axios.defaults.headers.common['Authorization'] = `Bearer ${newAccessToken}`;
+        }
       } catch(error) {
         // 若refresh token 失敗則導向至登入頁面
         this.$router.push('/login');
+        throw error;
       }
     },
     /**
diff --git a/tests/stores/login.test.js b/tests/stores/login.test.js
index 2055336..e806dc3 100644
--- a/tests/stores/login.test.js
+++ b/tests/stores/login.test.js
@@ -144,6 +144,47 @@ describe('loginStore', () => {
     expect(store.isLoggedIn).toBe(true);
   });
 
+  describe('refreshToken', () => {
+    it('sends request with correct config and updates tokens on success', async () => {
+      document.cookie = 'luciaRefreshToken=old-refresh-token';
+
+      axios.post.mockResolvedValue({
+        status: 200,
+        data: {
+          access_token: 'new-access-token',
+          refresh_token: 'new-refresh-token',
+        },
+      });
+
+      await store.refreshToken();
+
+      // Should call with content-type header (config must be defined)
+      expect(axios.post).toHaveBeenCalledWith(
+        '/api/oauth/token',
+        expect.objectContaining({
+          grant_type: 'refresh_token',
+          refresh_token: 'old-refresh-token',
+        }),
+        expect.objectContaining({
+          headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
+        }),
+      );
+
+      // Should update axios default Authorization header
+      expect(axios.defaults.headers.common['Authorization'])
+        .toBe('Bearer new-access-token');
+    });
+
+    it('redirects to login and re-throws on failure', async () => {
+      document.cookie = 'luciaRefreshToken=old-refresh-token';
+      axios.post.mockRejectedValue(new Error('401'));
+
+      await expect(store.refreshToken()).rejects.toThrow('401');
+
+      expect(store.$router.push).toHaveBeenCalledWith('/login');
+    });
+  });
+
   describe('expired', () => {
     it('is approximately 6 months in the future', () => {
       const now = new Date();