diff --git a/src/main/java/com/study/bookcafe/dao/BookRepository.java b/src/main/java/com/study/bookcafe/dao/BookRepository.java
index 03b647b..6fe945e 100644
--- a/src/main/java/com/study/bookcafe/dao/BookRepository.java
+++ b/src/main/java/com/study/bookcafe/dao/BookRepository.java
@@ -2,9 +2,10 @@
 
 import com.study.bookcafe.domain.Book;
 
+import java.util.Collection;
 import java.util.List;
 
 public interface BookRepository {
     Book findById(long bookId);
-    List<Book> findByIdList(List<Long> bookIdList);
+    List<Book> findByIdList(Collection<Long> bookIds);
 }
diff --git a/src/main/java/com/study/bookcafe/dao/BorrowRepository.java b/src/main/java/com/study/bookcafe/dao/BorrowRepository.java
index f7facdd..02fa92f 100644
--- a/src/main/java/com/study/bookcafe/dao/BorrowRepository.java
+++ b/src/main/java/com/study/bookcafe/dao/BorrowRepository.java
@@ -1,12 +1,14 @@
 package com.study.bookcafe.dao;
 
 import com.study.bookcafe.domain.Borrow;
+
+import java.util.Collection;
 import java.util.List;
 
 public interface BorrowRepository {
 
     Borrow findById(long borrowId);
     Borrow save(Borrow borrow);
-    List<Borrow> save(List<Borrow> borrowList);
+    List<Borrow> save(Collection<Borrow> borrows);
 
 }
diff --git a/src/main/java/com/study/bookcafe/dao/TestBookRepository.java b/src/main/java/com/study/bookcafe/dao/TestBookRepository.java
index 6e60ed6..3f8c7ae 100644
--- a/src/main/java/com/study/bookcafe/dao/TestBookRepository.java
+++ b/src/main/java/com/study/bookcafe/dao/TestBookRepository.java
@@ -2,31 +2,43 @@
 
 import com.study.bookcafe.domain.Book;
 import com.study.bookcafe.domain.Inventory;
+import com.study.bookcafe.entity.BookEntity;
+import com.study.bookcafe.mapper.BookMapper;
 import org.springframework.stereotype.Repository;
 
 import java.sql.Date;
 import java.time.LocalDate;
+import java.util.Collection;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
 @Repository
 public class TestBookRepository implements BookRepository {
-    public static Map<Long, Book> books = new HashMap<>(){{
-        put(1L, Book.builder().id(1L).ISBN(9788936433598L).title("채식주의자").author("한강").publisher("창비").publishDate(Date.valueOf(LocalDate.of(2007, 10, 30)))
+
+    private final BookMapper bookMapper;
+
+    public TestBookRepository(BookMapper bookMapper) {
+        this.bookMapper = bookMapper;
+    }
+
+    public static Map<Long, BookEntity> books = new HashMap<>(){{
+        put(1L, BookEntity.builder().id(1L).ISBN(9788936433598L).title("채식주의자").author("한강").publisher("창비").publishDate(Date.valueOf(LocalDate.of(2007, 10, 30)))
                 .price(35000).inventory(new Inventory(5)).build());
-        put(2L, Book.builder().id(2L).ISBN(9788954651134L).title("흰").author("한강").publisher("문학동네").publishDate(Date.valueOf(LocalDate.of(2018, 4, 25)))
+        put(2L, BookEntity.builder().id(2L).ISBN(9788954651134L).title("흰").author("한강").publisher("문학동네").publishDate(Date.valueOf(LocalDate.of(2018, 4, 25)))
                 .price(13000).inventory(new Inventory(0)).build());
     }};
 
     public Book findById(long bookId) {
-        return books.get(bookId);
+        BookEntity bookEntity = books.get(bookId);
+        return bookMapper.toBook(bookEntity);
     }
 
     @Override
-    public List<Book> findByIdList(List<Long> bookIdList) {
-        return bookIdList
-                .stream().filter(id -> books.containsKey(id))
+    public List<Book> findByIdList(Collection<Long> bookIds) {
+        List<BookEntity> bookEntities = bookIds.stream()
+                .filter(id -> books.containsKey(id))
                 .map(id -> books.get(id)).toList();
+        return bookMapper.toBookList(bookEntities);
     }
 }
diff --git a/src/main/java/com/study/bookcafe/dao/TestBorrowRepository.java b/src/main/java/com/study/bookcafe/dao/TestBorrowRepository.java
index ecf6730..466fedb 100644
--- a/src/main/java/com/study/bookcafe/dao/TestBorrowRepository.java
+++ b/src/main/java/com/study/bookcafe/dao/TestBorrowRepository.java
@@ -1,38 +1,51 @@
 package com.study.bookcafe.dao;
 
-import com.study.bookcafe.domain.Book;
 import com.study.bookcafe.domain.Borrow;
-import com.study.bookcafe.domain.Member;
+import com.study.bookcafe.entity.BookEntity;
+import com.study.bookcafe.entity.BorrowEntity;
+import com.study.bookcafe.entity.MemberEntity;
+import com.study.bookcafe.mapper.BorrowMapper;
 import org.springframework.stereotype.Repository;
 
+import java.util.Collection;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
 @Repository
 public class TestBorrowRepository implements BorrowRepository {
-    Map<Long, Borrow> borrows = new HashMap<>(){{
-        put(1L, Borrow.builder()
-                .member(Member.builder().id(1).build())
-                .book(Book.builder().id(1).ISBN(9788936433598L).build()).build());
-        put(2L, Borrow.builder()
-                .member(Member.builder().id(1).build())
-                .book(Book.builder().id(2).ISBN(9788936433598L).build()).build());
+
+    private final BorrowMapper borrowMapper;
+
+    public TestBorrowRepository(BorrowMapper borrowMapper) {
+        this.borrowMapper = borrowMapper;
+    }
+
+    Map<Long, BorrowEntity> borrows = new HashMap<>(){{
+        put(1L, BorrowEntity.builder()
+                .member(MemberEntity.builder().id(1).build())
+                .book(BookEntity.builder().id(1).ISBN(9788936433598L).build()).build());
+        put(2L, BorrowEntity.builder()
+                .member(MemberEntity.builder().id(1).build())
+                .book(BookEntity.builder().id(2).ISBN(9788936433598L).build()).build());
         put(3L, null);
     }};
 
     public Borrow findById(long borrowId) {
-        return borrows.get(borrowId);
+        BorrowEntity borrowEntity = borrows.get(borrowId);
+        return borrowMapper.toBorrow(borrowEntity);
     }
 
     public Borrow save(Borrow borrow) {
-        return borrow;
+        BorrowEntity borrowEntity = borrows.get(borrow.getId());
+        return borrowMapper.toBorrow(borrowEntity);
     }
 
     @Override
-    public List<Borrow> save(List<Borrow> borrowList) {
-        return borrowList
-                .stream().filter(borrow -> borrows.containsKey(borrow.getId()))
-                .map(borrow -> borrows.get(borrow.getId())).toList();
+    public List<Borrow> save(Collection<Borrow> borrows) {
+        List<BorrowEntity> borrowEntities = borrows
+                .stream().filter(borrow -> this.borrows.containsKey(borrow.getId()))
+                .map(borrow -> this.borrows.get(borrow.getId())).toList();
+        return borrowMapper.toBorrowList(borrowEntities);
     }
 }
diff --git a/src/main/java/com/study/bookcafe/service/BookService.java b/src/main/java/com/study/bookcafe/service/BookService.java
index 039a0aa..17b254f 100644
--- a/src/main/java/com/study/bookcafe/service/BookService.java
+++ b/src/main/java/com/study/bookcafe/service/BookService.java
@@ -2,6 +2,7 @@
 
 import com.study.bookcafe.domain.Book;
 
+import java.util.Collection;
 import java.util.List;
 
 public interface BookService {
@@ -9,5 +10,5 @@ public interface BookService {
     Book findById(long bookId);
 
     // 도서 목록 조회 (id list)
-    List<Book> findByIdList(List<Long> bookIdList);
+    List<Book> findByIdList(Collection<Long> bookIds);
 }
diff --git a/src/main/java/com/study/bookcafe/service/BookServiceImpl.java b/src/main/java/com/study/bookcafe/service/BookServiceImpl.java
index f15847b..5d5d57f 100644
--- a/src/main/java/com/study/bookcafe/service/BookServiceImpl.java
+++ b/src/main/java/com/study/bookcafe/service/BookServiceImpl.java
@@ -2,20 +2,18 @@
 
 import com.study.bookcafe.dao.BookRepository;
 import com.study.bookcafe.domain.Book;
-import com.study.bookcafe.mapper.BookMapper;
 import org.springframework.stereotype.Service;
 
+import java.util.Collection;
 import java.util.List;
 
 @Service
 public class BookServiceImpl implements BookService {
 
     private final BookRepository bookRepository;
-    private final BookMapper bookMapper;
 
-    public BookServiceImpl(BookRepository bookRepository, BookMapper bookMapper) {
+    public BookServiceImpl(BookRepository bookRepository) {
         this.bookRepository = bookRepository;
-        this.bookMapper = bookMapper;
     }
 
     /**
@@ -32,11 +30,11 @@ public Book findById(long bookId) {
     /**
      * 도서를 ID 목록으로 조회한다.
      *
-     * @param bookIdList 도서 ID 목록
+     * @param bookIds 도서 ID 목록
      * @return 도서 목록
      */
     @Override
-    public List<Book> findByIdList(List<Long> bookIdList) {
-        return bookRepository.findByIdList(bookIdList);
+    public List<Book> findByIdList(Collection<Long> bookIds) {
+        return bookRepository.findByIdList(bookIds);
     }
 }
diff --git a/src/main/java/com/study/bookcafe/service/BorrowService.java b/src/main/java/com/study/bookcafe/service/BorrowService.java
index ae955d2..04e9441 100644
--- a/src/main/java/com/study/bookcafe/service/BorrowService.java
+++ b/src/main/java/com/study/bookcafe/service/BorrowService.java
@@ -2,6 +2,7 @@
 
 import com.study.bookcafe.domain.Borrow;
 
+import java.util.Collection;
 import java.util.List;
 
 public interface BorrowService {
@@ -9,5 +10,5 @@ public interface BorrowService {
     Borrow save(Borrow borrow);
 
     // 여러 대출 저장
-    List<Borrow> save(List<Borrow> borrowList);
-}
+    List<Borrow> save(Collection<Borrow> borrows);
+}
\ No newline at end of file
diff --git a/src/main/java/com/study/bookcafe/service/BorrowServiceImpl.java b/src/main/java/com/study/bookcafe/service/BorrowServiceImpl.java
index 73b12b8..f25de28 100644
--- a/src/main/java/com/study/bookcafe/service/BorrowServiceImpl.java
+++ b/src/main/java/com/study/bookcafe/service/BorrowServiceImpl.java
@@ -2,20 +2,17 @@
 
 import com.study.bookcafe.dao.BorrowRepository;
 import com.study.bookcafe.domain.Borrow;
-import com.study.bookcafe.entity.BorrowEntity;
-import com.study.bookcafe.mapper.BorrowMapper;
 import org.springframework.stereotype.Service;
 
+import java.util.Collection;
 import java.util.List;
 
 @Service
 public class BorrowServiceImpl implements BorrowService {
     private final BorrowRepository borrowRepository;
-    private final BorrowMapper borrowMapper;
 
-    public BorrowServiceImpl(BorrowRepository borrowRepository, BorrowMapper borrowMapper) {
+    public BorrowServiceImpl(BorrowRepository borrowRepository) {
         this.borrowRepository = borrowRepository;
-        this.borrowMapper = borrowMapper;
     }
 
     /**
@@ -31,12 +28,12 @@ public Borrow save(Borrow borrow) {
     /**
      * 새로운 여러 대출들을 저장한다.
      *
-     * @param borrowList 대출 목록
+     * @param borrows 대출 목록
      * @return 생성한 대출 정보 목록
      */
     @Override
-    public List<Borrow> save(List<Borrow> borrowList) {
-        List<BorrowEntity> borrowEntityList = borrowMapper.toBorrowEntityList(borrowList);
-        return borrowMapper.toBorrowList(borrowEntityList);
+    public List<Borrow> save(Collection<Borrow> borrows) {
+        return borrowRepository.save(borrows);
     }
+
 }
diff --git a/src/main/java/com/study/bookcafe/service/MemberService.java b/src/main/java/com/study/bookcafe/service/MemberService.java
index 9b8fd49..6df6bb5 100644
--- a/src/main/java/com/study/bookcafe/service/MemberService.java
+++ b/src/main/java/com/study/bookcafe/service/MemberService.java
@@ -3,6 +3,7 @@
 import com.study.bookcafe.domain.Borrow;
 import com.study.bookcafe.domain.Member;
 
+import java.util.Collection;
 import java.util.List;
 
 public interface MemberService {
@@ -11,5 +12,5 @@ public interface MemberService {
     Member findById(long memberId);
 
     // 도서 대출
-    List<Borrow> borrowBook(long memberId, List<Long> bookIdList);
+    List<Borrow> borrowBook(long memberId, Collection<Long> bookIds);
 }
diff --git a/src/main/java/com/study/bookcafe/service/MemberServiceImpl.java b/src/main/java/com/study/bookcafe/service/MemberServiceImpl.java
index ea843a0..4e37722 100644
--- a/src/main/java/com/study/bookcafe/service/MemberServiceImpl.java
+++ b/src/main/java/com/study/bookcafe/service/MemberServiceImpl.java
@@ -4,9 +4,9 @@
 import com.study.bookcafe.domain.Book;
 import com.study.bookcafe.domain.Borrow;
 import com.study.bookcafe.domain.Member;
-import com.study.bookcafe.mapper.MemberMapper;
 import org.springframework.stereotype.Service;
 
+import java.util.Collection;
 import java.util.List;
 
 @Service
@@ -15,13 +15,11 @@ public class MemberServiceImpl implements MemberService {
     private final MemberRepository memberRepository;
     private final BorrowService borrowService;
     private final BookService bookService;
-    private final MemberMapper memberMapper;
 
-    public MemberServiceImpl(MemberRepository memberRepository, BorrowService borrowService, BookService bookService, MemberMapper memberMapper) {
+    public MemberServiceImpl(MemberRepository memberRepository, BorrowService borrowService, BookService bookService) {
         this.memberRepository = memberRepository;
         this.borrowService = borrowService;
         this.bookService = bookService;
-        this.memberMapper = memberMapper;
     }
 
     /**
@@ -39,17 +37,17 @@ public Member findById(long memberId) {
      * 회원이 도서를 대출한다.
      *
      * @param memberId      회원 ID
-     * @param bookIdList    도서 ID 목록
+     * @param bookIds    도서 ID 목록
      * @return 대출 정보
      */
     @Override
-    public List<Borrow> borrowBook(long memberId, List<Long> bookIdList) {
+    public List<Borrow> borrowBook(long memberId, Collection<Long> bookIds) {
         Member member = findById(memberId);
-        List<Book> bookList = bookService.findByIdList(bookIdList);
-        List<Borrow> borrowList = member.borrowBook(bookList);
+        List<Book> books = bookService.findByIdList(bookIds);
+        List<Borrow> borrows = member.borrowBook(books);
 
-        if(borrowList.isEmpty()) return borrowList;
+        if(borrows.isEmpty()) return borrows;
 
-        return borrowService.save(borrowList);
+        return borrowService.save(borrows);
     }
 }
\ No newline at end of file