diff --git a/src/main/java/com/ceos/bankids/mapper/UserMapper.java b/src/main/java/com/ceos/bankids/mapper/UserMapper.java
index 1247eb1..8681968 100644
--- a/src/main/java/com/ceos/bankids/mapper/UserMapper.java
+++ b/src/main/java/com/ceos/bankids/mapper/UserMapper.java
@@ -68,7 +68,7 @@ public UserDTO updateUserType(User user, UserTypeRequest userTypeRequest) {
         }
 
         // 날짜가 입력됐다면 유효한지 검사
-        if (userTypeRequest.getBirthday() != "") {
+        if (userTypeRequest.getBirthday() != "99999999") {
             SimpleDateFormat dateFormat = new SimpleDateFormat("yyyyMMdd");
             dateFormat.setLenient(false);
             try {
diff --git a/src/test/java/com/ceos/bankids/unit/controller/UserControllerTest.java b/src/test/java/com/ceos/bankids/unit/controller/UserControllerTest.java
index 8f37a13..ffc8ba3 100644
--- a/src/test/java/com/ceos/bankids/unit/controller/UserControllerTest.java
+++ b/src/test/java/com/ceos/bankids/unit/controller/UserControllerTest.java
@@ -123,7 +123,7 @@ public void testIfUserTypePatchWithoutBirthdaySucceedReturnResult() {
             .provider("kakao")
             .refreshToken("token")
             .build();
-        UserTypeRequest userTypeRequest = new UserTypeRequest("", false, true);
+        UserTypeRequest userTypeRequest = new UserTypeRequest("99999999", false, true);
         UserRepository mockUserRepository = Mockito.mock(UserRepository.class);
         Mockito.when(mockUserRepository.findById(1L))
             .thenReturn(Optional.ofNullable(user));
@@ -163,7 +163,7 @@ public void testIfUserTypePatchWithoutBirthdaySucceedReturnResult() {
         CommonResponse<UserDTO> result = userController.patchUserType(user, userTypeRequest);
 
         // then
-        user.setBirthday("");
+        user.setBirthday("99999999");
         user.setIsFemale(false);
         user.setIsKid(true);
         UserDTO userDTO = new UserDTO(user);