diff --git a/backend/src/main/java/com/example/todoapp/controller/ToBuysController.java b/backend/src/main/java/com/example/todoapp/controller/ToBuysController.java
index 7b81ea3..54f643c 100644
--- a/backend/src/main/java/com/example/todoapp/controller/ToBuysController.java
+++ b/backend/src/main/java/com/example/todoapp/controller/ToBuysController.java
@@ -10,6 +10,7 @@ package com.example.todoapp.controller;
 import com.example.todoapp.dto.DeleteToBuyRequest;
 import com.example.todoapp.dto.ToBuyResponse;
 import com.example.todoapp.dto.ToBuysDTO;
+import com.example.todoapp.dto.ToBuysBuyDTO;
 import com.example.todoapp.model.ToBuys;
 import com.example.todoapp.model.User;
 import com.example.todoapp.repository.UserRepository;
@@ -137,4 +138,13 @@ public class ToBuysController {
 
         return ResponseEntity.ok(response);
     }
+
+    @PostMapping("/{id}")
+    public ResponseEntity<?> buyToBuys(
+        Authentication authentication,
+        @PathVariable("id") ToBuysBuyDTO toBuysbuyDTO) {
+        toBuysService.buyToBuys(authentication.getName(), toBuysbuyDTO);
+        return ResponseEntity.ok().build();
+    }
+
 }
\ No newline at end of file
diff --git a/backend/src/main/java/com/example/todoapp/dto/ToBuysBuyDTO.java b/backend/src/main/java/com/example/todoapp/dto/ToBuysBuyDTO.java
new file mode 100644
index 0000000..fef1aac
--- /dev/null
+++ b/backend/src/main/java/com/example/todoapp/dto/ToBuysBuyDTO.java
@@ -0,0 +1,18 @@
+package com.example.todoapp.dto;
+
+import lombok.Data;
+/**
+ * カテゴリDTOクラス
+ * このクラスはタスクのカテゴリ情報を表します。
+ * カテゴリは名前、色、所有ユーザーなどの情報を持ちます。
+ * 
+ */
+
+ @Data
+ public class ToBuysBuyDTO {
+    private Long  stuff_id;
+    private int amount;
+    private String shop;
+    private String stuff_name; 
+    private String category;
+ }
\ No newline at end of file
diff --git a/backend/src/main/java/com/example/todoapp/service/ToBuysService.java b/backend/src/main/java/com/example/todoapp/service/ToBuysService.java
index 3fcaee2..fd4d50e 100644
--- a/backend/src/main/java/com/example/todoapp/service/ToBuysService.java
+++ b/backend/src/main/java/com/example/todoapp/service/ToBuysService.java
@@ -8,10 +8,15 @@
 
 package com.example.todoapp.service;
 
+import com.example.todoapp.util.MessageUtils;
+
 import com.example.todoapp.dto.ToBuysDTO;
+import com.example.todoapp.dto.ToBuysBuyDTO;
+import com.example.todoapp.model.Stocks;
 import com.example.todoapp.model.Stuffs;
 import com.example.todoapp.model.ToBuys;
 import com.example.todoapp.model.User;
+import com.example.todoapp.repository.StocksRepository;
 import com.example.todoapp.repository.StuffsRepository;
 import com.example.todoapp.repository.ToBuysRepository;
 import com.example.todoapp.repository.UserRepository;
@@ -19,6 +24,7 @@ import com.example.todoapp.repository.UserRepository;
 import jakarta.transaction.Transactional;
 
 import org.springframework.security.core.Authentication;
+import org.springframework.security.core.userdetails.UsernameNotFoundException;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Service;
 
@@ -44,6 +50,12 @@ public class ToBuysService {
 
     @Autowired
     private StuffsRepository stuffsRepository;
+    
+    @Autowired
+    private StuffsRepository stocksRepository;
+
+    @Autowired
+    private MessageUtils messageUtils;
 
 
     /**
@@ -151,4 +163,34 @@ public class ToBuysService {
     public int deleteToBuyByIds(Long userId, int tobuyId) {
         return toBuysRepository.deleteByUserIdAndTobuyId(userId, tobuyId);
     }
+
+    public Stocks buyToBuys(String username, ToBuysBuyDTO dto) {
+        // ユーザー情報を取得
+        User user = getUserByUsername(username);
+        // 新しい在庫を作成
+        Stocks stock = new Stocks();
+        stock.setStuffs(dto.getStuff_id());
+        stock.setUser_id(user);
+        stock.setAmount(dto.getAmount());
+        stock.setPrice(dto.getPrice());
+        stock.setLast_update(dto.getLast_update());
+        stock.setBuy_date(dto.getBuy_date());
+        stock.setExp_date(dto.getExp_date());
+        deleteToBuys(toBuyDTO);
+        // データベースに保存
+        return stockRepository.save(stock);
+    }
+
+    /**
+     * ユーザー名からユーザーエンティティを取得する
+     *
+     * @param username ユーザー名
+     * @return ユーザーエンティティ
+     * @throws UsernameNotFoundException ユーザーが見つからない場合
+     */
+    private User getUserByUsername(String username) {
+        return userRepository.findByUsername(username)
+            .orElseThrow(() -> new UsernameNotFoundException(messageUtils.getMessage("error.auth.user.not.found.with.name", new Object[]{username})));
+    }
+
 }
\ No newline at end of file