diff --git a/src/main/java/life/mosu/mosuserver/application/application/ApplicationService.java b/src/main/java/life/mosu/mosuserver/application/application/ApplicationService.java
index 09362530..b3899f1f 100644
--- a/src/main/java/life/mosu/mosuserver/application/application/ApplicationService.java
+++ b/src/main/java/life/mosu/mosuserver/application/application/ApplicationService.java
@@ -61,7 +61,7 @@ public CreateApplicationResponse apply(Long userId, ApplicationRequest request)
 
     @Transactional
     public CreateApplicationResponse applyByGuest(ApplicationGuestRequest request) {
-        Long userId = userService.saveUser(request.toUserJpaEntity());
+        Long userId = userService.saveOrGetUser(request.toUserJpaEntity());
         CreateApplicationResponse response = handleApplication(
                 userId,
                 List.of(request.examApplication().examId()),
diff --git a/src/main/java/life/mosu/mosuserver/application/user/UserService.java b/src/main/java/life/mosu/mosuserver/application/user/UserService.java
index be991f70..ce3b0918 100644
--- a/src/main/java/life/mosu/mosuserver/application/user/UserService.java
+++ b/src/main/java/life/mosu/mosuserver/application/user/UserService.java
@@ -37,12 +37,16 @@ public void syncUserInfoFromProfile(UserJpaEntity user, ProfileJpaEntity profile
         }
     }
 
-    public Long saveUser(UserJpaEntity user) {
-        Long userId = userJpaRepository.save(user).getId();
-        if (userId == null) {
-            throw new CustomRuntimeException(ErrorCode.USER_SAVE_FAILED);
-        }
-        return userId;
+    public Long saveOrGetUser(UserJpaEntity user) {
+        return userJpaRepository.findByPhoneNumber(user.getPhoneNumber())
+                .map(UserJpaEntity::getId)
+                .orElseGet(() -> {
+                    Long userId = userJpaRepository.save(user).getId();
+                    if (userId == null) {
+                        throw new CustomRuntimeException(ErrorCode.USER_SAVE_FAILED);
+                    }
+                    return userId;
+                });
     }
 
     public UserInfoResponse getUserInfo(Long userId) {