diff --git a/src/main/java/com/ogjg/daitgym/user/controller/UserController.java b/src/main/java/com/ogjg/daitgym/user/controller/UserController.java
index e755dbb9..caa10d78 100644
--- a/src/main/java/com/ogjg/daitgym/user/controller/UserController.java
+++ b/src/main/java/com/ogjg/daitgym/user/controller/UserController.java
@@ -50,10 +50,10 @@ public ApiResponse<?> logout(HttpServletResponse response,
      */
     @GetMapping("/check-duplication")
     public ApiResponse<?> checkNicknameDuplication(
-            @RequestParam("nickname") String nickname,
+            @RequestParam("nickname") String newNickname,
             @AuthenticationPrincipal OAuth2JwtUserDetails userDetails
     ) {
-        String message = userService.checkNicknameDuplication(nickname, userDetails.getNickname());
+        String message = userService.checkNicknameDuplication(userDetails.getNickname(), newNickname);
         return new ApiResponse<>(ErrorCode.SUCCESS.changeMessage(message));
     }
 
diff --git a/src/main/java/com/ogjg/daitgym/user/service/UserHelper.java b/src/main/java/com/ogjg/daitgym/user/service/UserHelper.java
index f45cc667..337e7abf 100644
--- a/src/main/java/com/ogjg/daitgym/user/service/UserHelper.java
+++ b/src/main/java/com/ogjg/daitgym/user/service/UserHelper.java
@@ -25,10 +25,14 @@ public User findUserByEmail(String email) {
     }
 
     public boolean isUserNotFoundByEmail(String loginEmail) {
-        return !userRepository.findByEmail(loginEmail).isPresent();
+        return userRepository.findByEmail(loginEmail).isEmpty();
     }
 
-    public boolean isNicknameAlreadyExist(String nickname, String newNickname) {
-        return !nickname.equals(newNickname) && userRepository.findByNickname(newNickname).isPresent();
+    public boolean isNicknameAlreadyExist(String loginNickname, String newNickname) {
+        return isNotMyNickname(loginNickname, newNickname) && userRepository.findByNickname(newNickname).isPresent();
+    }
+
+    private boolean isNotMyNickname(String loginNickname, String newNickname) {
+        return !loginNickname.equals(newNickname);
     }
 }
diff --git a/src/main/java/com/ogjg/daitgym/user/service/UserService.java b/src/main/java/com/ogjg/daitgym/user/service/UserService.java
index 588104c8..0475fefc 100644
--- a/src/main/java/com/ogjg/daitgym/user/service/UserService.java
+++ b/src/main/java/com/ogjg/daitgym/user/service/UserService.java
@@ -272,8 +272,8 @@ public EditInitialNicknameResponse editInitialNickname(String loginEmail, EditNi
     }
 
     @Transactional(readOnly = true)
-    public String checkNicknameDuplication(String nickname, String newNickname) {
-        if (userHelper.isNicknameAlreadyExist(nickname, newNickname)) {
+    public String checkNicknameDuplication(String loginNickname, String newNickname) {
+        if (userHelper.isNicknameAlreadyExist(loginNickname, newNickname)) {
             return "중복";
         }
         return "사용가능";