diff --git a/src/main/java/LeejuButU/BidCycle/domain/member/service/MemberService.java b/src/main/java/LeejuButU/BidCycle/domain/member/service/MemberService.java
new file mode 100644
index 0000000..c7bbe35
--- /dev/null
+++ b/src/main/java/LeejuButU/BidCycle/domain/member/service/MemberService.java
@@ -0,0 +1,66 @@
+package LeejuButU.BidCycle.domain.member.service;
+
+import LeejuButU.BidCycle.domain.member.domain.Member;
+import LeejuButU.BidCycle.domain.member.repository.MemberRepository;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.util.List;
+import java.util.Optional;
+
+@Service
+@Transactional(readOnly = true)
+@RequiredArgsConstructor
+public class MemberService {
+
+    private final MemberRepository memberRepository;
+
+    //회원ID로 회원 조회 (회원이 존재하지 않으면 예외 발생)
+    private Member findByIdOrThrow(Long memberId){
+        return memberRepository.findById(memberId)
+                .orElseThrow(() -> new IllegalArgumentException("해당 회원을 찾을 수 없습니다."));
+    }
+
+    //회원 가입
+    @Transactional
+    public Long join(Member member){
+        if(memberRepository.existsById(member.getMemberId())){
+            throw new IllegalStateException("이미 존재하는 회원입니다.");
+        }
+        memberRepository.save(member);
+        return member.getMemberId();
+    }
+
+    //전체 회원 조회
+    public List<Member> findMembers(){
+        return memberRepository.findAll();
+    }
+
+    //회원 한 명 조회
+    public Member findOne(Long memberId){
+        return findByIdOrThrow(memberId);
+    }
+
+    // 회원 정보 변경
+    @Transactional
+    public void updateMember(Long memberId, Member updatedMember) {
+        Member member = findByIdOrThrow(memberId);
+
+        // 변경할 정보를 새로운 정보로 업데이트
+        member.updatePassword(updatedMember.getPassword());
+        member.updateNickname(updatedMember.getNickname());
+        member.updateTown(updatedMember.getTown());
+
+        // 변경된 정보를 저장
+        memberRepository.save(member);
+    }
+
+    // 회원 탈퇴
+    @Transactional
+    public void withdrawMember(Long memberId) {
+        Member member = findByIdOrThrow(memberId);
+        memberRepository.delete(member);
+    }
+
+}