diff --git a/src/main/java/roomescape/member/business/MemberService.kt b/src/main/java/roomescape/member/business/MemberService.kt
index b531a0fc..2949740c 100644
--- a/src/main/java/roomescape/member/business/MemberService.kt
+++ b/src/main/java/roomescape/member/business/MemberService.kt
@@ -1,47 +1,40 @@
-package roomescape.member.business;
+package roomescape.member.business
 
-import java.util.List;
-
-import org.springframework.http.HttpStatus;
-import org.springframework.stereotype.Service;
-import org.springframework.transaction.annotation.Transactional;
-
-import roomescape.member.infrastructure.entity.Member;
-import roomescape.member.infrastructure.entity.MemberRepository;
-import roomescape.member.web.MemberResponse;
-import roomescape.member.web.MembersResponse;
-import roomescape.system.exception.ErrorType;
-import roomescape.system.exception.RoomEscapeException;
+import org.springframework.data.repository.findByIdOrNull
+import org.springframework.http.HttpStatus
+import org.springframework.stereotype.Service
+import org.springframework.transaction.annotation.Transactional
+import roomescape.member.infrastructure.entity.Member
+import roomescape.member.infrastructure.entity.MemberRepository
+import roomescape.member.web.MembersResponse
+import roomescape.member.web.toResponse
+import roomescape.system.exception.ErrorType
+import roomescape.system.exception.RoomEscapeException
 
 @Service
-public class MemberService {
+@Transactional(readOnly = true)
+class MemberService(
+        private val memberRepository: MemberRepository
+) {
+    fun readAllMembers(): MembersResponse = MembersResponse(
+            memberRepository.findAll()
+                    .map { it.toResponse() }
+                    .toList()
+    )
 
-	private final MemberRepository memberRepository;
+    fun findById(memberId: Long): Member = memberRepository.findByIdOrNull(memberId)
+            ?: throw RoomEscapeException(
+                    ErrorType.MEMBER_NOT_FOUND,
+                    String.format("[memberId: %d]", memberId),
+                    HttpStatus.BAD_REQUEST
+            )
 
-	public MemberService(MemberRepository memberRepository) {
-		this.memberRepository = memberRepository;
-	}
-
-	@Transactional(readOnly = true)
-	public MembersResponse findAllMembers() {
-		List<MemberResponse> response = memberRepository.findAll().stream()
-			.map(MemberResponse::fromEntity)
-			.toList();
-
-		return new MembersResponse(response);
-	}
-
-	@Transactional(readOnly = true)
-	public Member findMemberById(Long memberId) {
-		return memberRepository.findById(memberId)
-			.orElseThrow(() -> new RoomEscapeException(ErrorType.MEMBER_NOT_FOUND,
-				String.format("[memberId: %d]", memberId), HttpStatus.BAD_REQUEST));
-	}
-
-	@Transactional(readOnly = true)
-	public Member findMemberByEmailAndPassword(String email, String password) {
-		return memberRepository.findByEmailAndPassword(email, password)
-			.orElseThrow(() -> new RoomEscapeException(ErrorType.MEMBER_NOT_FOUND,
-				String.format("[email: %s, password: %s]", email, password), HttpStatus.BAD_REQUEST));
-	}
+    fun findMemberByEmailAndPassword(email: String, password: String): Member =
+            memberRepository.findByEmailAndPassword(email, password)
+                    ?: throw RoomEscapeException(
+                            ErrorType.MEMBER_NOT_FOUND,
+                            String.format("[email: %s, password: %s]", email, password),
+                            HttpStatus.BAD_REQUEST
+                    )
 }
+
diff --git a/src/main/java/roomescape/member/infrastructure/entity/MemberRepository.kt b/src/main/java/roomescape/member/infrastructure/entity/MemberRepository.kt
index 8c35fb30..a681120a 100644
--- a/src/main/java/roomescape/member/infrastructure/entity/MemberRepository.kt
+++ b/src/main/java/roomescape/member/infrastructure/entity/MemberRepository.kt
@@ -1,10 +1,7 @@
-package roomescape.member.infrastructure.entity;
+package roomescape.member.infrastructure.entity
 
-import java.util.Optional;
+import org.springframework.data.jpa.repository.JpaRepository
 
-import org.springframework.data.jpa.repository.JpaRepository;
-
-public interface MemberRepository extends JpaRepository<Member, Long> {
-
-	Optional<Member> findByEmailAndPassword(String email, String password);
+interface MemberRepository : JpaRepository<Member, Long> {
+    fun findByEmailAndPassword(email: String, password: String): Member?
 }
diff --git a/src/main/java/roomescape/reservation/service/ReservationService.java b/src/main/java/roomescape/reservation/service/ReservationService.java
index b82d42eb..9304e8fe 100644
--- a/src/main/java/roomescape/reservation/service/ReservationService.java
+++ b/src/main/java/roomescape/reservation/service/ReservationService.java
@@ -9,8 +9,8 @@ import org.springframework.http.HttpStatus;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
-import roomescape.member.infrastructure.entity.Member;
 import roomescape.member.business.MemberService;
+import roomescape.member.infrastructure.entity.Member;
 import roomescape.reservation.domain.Reservation;
 import roomescape.reservation.domain.ReservationStatus;
 import roomescape.reservation.domain.ReservationTime;
@@ -147,7 +147,7 @@ public class ReservationService {
 		ReservationStatus status) {
 		ReservationTime time = reservationTimeService.findTimeById(timeId);
 		Theme theme = themeService.findThemeById(themeId);
-		Member member = memberService.findMemberById(memberId);
+		Member member = memberService.findById(memberId);
 
 		validateDateAndTime(date, time);
 		return new Reservation(date, time, theme, member, status);
@@ -213,7 +213,7 @@ public class ReservationService {
 	}
 
 	private void validateIsMemberAdmin(Long memberId) {
-		Member member = memberService.findMemberById(memberId);
+		Member member = memberService.findById(memberId);
 		if (member.isAdmin()) {
 			return;
 		}
diff --git a/src/main/java/roomescape/system/auth/interceptor/AdminInterceptor.java b/src/main/java/roomescape/system/auth/interceptor/AdminInterceptor.java
index 1e372aad..0788419d 100644
--- a/src/main/java/roomescape/system/auth/interceptor/AdminInterceptor.java
+++ b/src/main/java/roomescape/system/auth/interceptor/AdminInterceptor.java
@@ -10,8 +10,8 @@ import org.springframework.web.servlet.HandlerInterceptor;
 import jakarta.servlet.http.Cookie;
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
-import roomescape.member.infrastructure.entity.Member;
 import roomescape.member.business.MemberService;
+import roomescape.member.infrastructure.entity.Member;
 import roomescape.system.auth.annotation.Admin;
 import roomescape.system.auth.jwt.JwtHandler;
 import roomescape.system.exception.ErrorType;
@@ -44,7 +44,7 @@ public class AdminInterceptor implements HandlerInterceptor {
 		try {
 			Cookie token = getToken(request);
 			Long memberId = jwtHandler.getMemberIdFromToken(token.getValue());
-			member = memberService.findMemberById(memberId);
+			member = memberService.findById(memberId);
 		} catch (RoomEscapeException e) {
 			response.sendRedirect("/login");
 			throw e;
diff --git a/src/main/java/roomescape/system/auth/interceptor/LoginInterceptor.java b/src/main/java/roomescape/system/auth/interceptor/LoginInterceptor.java
index c82343eb..6522fb0a 100644
--- a/src/main/java/roomescape/system/auth/interceptor/LoginInterceptor.java
+++ b/src/main/java/roomescape/system/auth/interceptor/LoginInterceptor.java
@@ -10,8 +10,8 @@ import org.springframework.web.servlet.HandlerInterceptor;
 import jakarta.servlet.http.Cookie;
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
-import roomescape.member.infrastructure.entity.Member;
 import roomescape.member.business.MemberService;
+import roomescape.member.infrastructure.entity.Member;
 import roomescape.system.auth.annotation.LoginRequired;
 import roomescape.system.auth.jwt.JwtHandler;
 import roomescape.system.exception.ErrorType;
@@ -44,7 +44,7 @@ public class LoginInterceptor implements HandlerInterceptor {
 		try {
 			Cookie token = getToken(request);
 			Long memberId = jwtHandler.getMemberIdFromToken(token.getValue());
-			member = memberService.findMemberById(memberId);
+			member = memberService.findById(memberId);
 			return member != null;
 		} catch (RoomEscapeException e) {
 			response.sendRedirect("/login");
diff --git a/src/main/java/roomescape/system/auth/service/AuthService.java b/src/main/java/roomescape/system/auth/service/AuthService.java
index 8fa1447a..695031f3 100644
--- a/src/main/java/roomescape/system/auth/service/AuthService.java
+++ b/src/main/java/roomescape/system/auth/service/AuthService.java
@@ -2,8 +2,8 @@ package roomescape.system.auth.service;
 
 import org.springframework.stereotype.Service;
 
-import roomescape.member.infrastructure.entity.Member;
 import roomescape.member.business.MemberService;
+import roomescape.member.infrastructure.entity.Member;
 import roomescape.system.auth.dto.LoginCheckResponse;
 import roomescape.system.auth.dto.LoginRequest;
 import roomescape.system.auth.jwt.JwtHandler;
@@ -27,7 +27,7 @@ public class AuthService {
 	}
 
 	public LoginCheckResponse checkLogin(Long memberId) {
-		Member member = memberService.findMemberById(memberId);
+		Member member = memberService.findById(memberId);
 
 		return new LoginCheckResponse(member.getName());
 	}