diff --git a/backend/app.py b/backend/app.py
index 42aba17..d7f5a6c 100644
--- a/backend/app.py
+++ b/backend/app.py
@@ -937,10 +937,14 @@ def claim_kakao_callback():
     kakao_phone_raw = user_info.get('phone_number')
     kakao_phone = normalize_kakao_phone(kakao_phone_raw)
 
-    # 카카오에서 받은 생년월일 조합 (YYYY-MMDD)
+    # 카카오에서 받은 생년월일 조합
     kakao_birthday = None
-    if user_info.get('birthyear') and user_info.get('birthday'):
-        kakao_birthday = f"{user_info['birthyear']}-{user_info['birthday'][:2]}-{user_info['birthday'][2:]}"
+    kakao_bday = user_info.get('birthday')  # MMDD 형식
+    if kakao_bday and len(kakao_bday) == 4:
+        if user_info.get('birthyear'):
+            kakao_birthday = f"{user_info['birthyear']}-{kakao_bday[:2]}-{kakao_bday[2:]}"  # YYYY-MM-DD
+        else:
+            kakao_birthday = f"{kakao_bday[:2]}-{kakao_bday[2:]}"  # MM-DD (연도 없음)
 
     # 7. 분기: 전화번호가 있으면 자동 적립, 없으면 폰 입력 폼
     if kakao_phone:
diff --git a/backend/templates/admin.html b/backend/templates/admin.html
index 6e99e1d..b077eac 100644
--- a/backend/templates/admin.html
+++ b/backend/templates/admin.html
@@ -885,7 +885,7 @@
                         ${user.birthday ? `
                         <div>
                             <div style="color: #868e96; font-size: 13px; margin-bottom: 6px;">🎂 생일</div>
-                            <div style="color: #ec4899; font-size: 16px; font-weight: 600;">${user.birthday.slice(0,2)}월 ${user.birthday.slice(2,4)}일</div>
+                            <div style="color: #ec4899; font-size: 16px; font-weight: 600;">${user.birthday.includes('-') ? user.birthday.split('-')[0] + '월 ' + user.birthday.split('-')[1] + '일' : user.birthday.slice(0,2) + '월 ' + user.birthday.slice(2,4) + '일'}</div>
                         </div>
                         ` : ''}
                     </div>