diff --git a/src/test/java/com/depromeet/domain/member/application/MemberServiceTest.java b/src/test/java/com/depromeet/domain/member/application/MemberServiceTest.java
index ed2394c5d..8d5143b80 100644
--- a/src/test/java/com/depromeet/domain/member/application/MemberServiceTest.java
+++ b/src/test/java/com/depromeet/domain/member/application/MemberServiceTest.java
@@ -12,6 +12,7 @@
 import com.depromeet.domain.member.domain.Member;
 import com.depromeet.domain.member.domain.OauthInfo;
 import com.depromeet.domain.member.domain.Profile;
+import com.depromeet.domain.member.dto.request.NicknameUpdateRequest;
 import com.depromeet.domain.member.dto.response.MemberSearchResponse;
 import com.depromeet.domain.member.dto.response.MemberSocialInfoResponse;
 import com.depromeet.global.error.exception.CustomException;
@@ -255,4 +256,45 @@ void setUp() {
             assertEquals(FollowStatus.FOLLOWED_BY_ME, responses.get(2).followStatus());
         }
     }
+
+    @Nested
+    class 닉네임을_변경할떄 {
+        @Test
+        void 다른_유저와_닉네임이_중복되면_예외가_발생한다() {
+            // given
+            OauthInfo oauthInfo =
+                    OauthInfo.createOauthInfo("testOauthId", "testOauthProvider", "testEmail");
+            saveAndRegisterMember(oauthInfo);
+
+            Member anotherMember =
+                    Member.createNormalMember(
+                            OauthInfo.createOauthInfo(
+                                    "testOauthId2", "testOauthProvider2", "testEmail2"),
+                            "testNickname2");
+            memberRepository.save(anotherMember);
+
+            // when & then
+            NicknameUpdateRequest request = new NicknameUpdateRequest("testNickname2");
+            assertThatThrownBy(() -> memberService.updateMemberNickname(request))
+                    .isInstanceOf(CustomException.class)
+                    .hasMessage(ErrorCode.MEMBER_ALREADY_NICKNAME.getMessage());
+        }
+
+        @Test
+        void 닉네임이_중복되지_않으면_변경된다() {
+            // given
+            OauthInfo oauthInfo =
+                    OauthInfo.createOauthInfo("testOauthId", "testOauthProvider", "testEmail");
+            saveAndRegisterMember(oauthInfo);
+
+            // when
+            NicknameUpdateRequest request = new NicknameUpdateRequest("testNickname2");
+
+            // then
+            assertDoesNotThrow(() -> memberService.updateMemberNickname(request));
+
+            Member member = memberRepository.findById(1L).get();
+            assertEquals("testNickname2", member.getProfile().getNickname());
+        }
+    }
 }