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 799d3f9..d5753e9 100644
--- a/backend/src/main/java/com/example/todoapp/controller/ToBuysController.java
+++ b/backend/src/main/java/com/example/todoapp/controller/ToBuysController.java
@@ -92,7 +92,6 @@ public class ToBuysController {
     }
 
 
-
     /**
      * 指定されたユーザーIDに基づいてすべての「買うもの」リストを取得する
      *
@@ -125,9 +124,6 @@ public class ToBuysController {
                 })
                 .collect(Collectors.toList());
 
-        // Map<String, Object> responseBody = new HashMap<>();
-        // responseBody.put("tobuy_array", responseList);
-
         return ResponseEntity.ok(responseList);
     }
 
@@ -189,7 +185,8 @@ public class ToBuysController {
             Authentication authentication) {
 
         Long recipeId = payload.get("recipeId");
-        List<ToBuyResponseDTO> responseList = toBuysService.addByRecipeId(recipeId, authentication);
+        Long servings = payload.get("servings");
+        List<ToBuyResponseDTO> responseList = toBuysService.addByRecipeId(recipeId, servings,authentication);
 
         //shopのフィールドを削除
         List<Map<String, Object>> filteredList = responseList.stream()
diff --git a/backend/src/main/java/com/example/todoapp/service/StocksService.java b/backend/src/main/java/com/example/todoapp/service/StocksService.java
index bd2dc19..51a142f 100644
--- a/backend/src/main/java/com/example/todoapp/service/StocksService.java
+++ b/backend/src/main/java/com/example/todoapp/service/StocksService.java
@@ -1,6 +1,5 @@
 package com.example.todoapp.service;
 
-import com.example.todoapp.dto.StockDTO;
 import com.example.todoapp.dto.AddStocksDTO;
 import com.example.todoapp.dto.UpdateStockRequest;
 import com.example.todoapp.model.Stocks;
@@ -57,9 +56,6 @@ public class StocksService {
         } else {
             // 材料情報を取得
             Optional<Stuffs> existstuffs = stuffsRepository.findById(stock.getStuffId());
-            if (existstuffs == null) {
-                throw new RuntimeException("材料がありません");
-            }
             stuffs = existstuffs.get();
         }
 
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 678aae6..fe3bfe7 100644
--- a/backend/src/main/java/com/example/todoapp/service/ToBuysService.java
+++ b/backend/src/main/java/com/example/todoapp/service/ToBuysService.java
@@ -91,14 +91,22 @@ public class ToBuysService {
             stuff = optStuff.get();
         }
 
-        ToBuys toBuys = new ToBuys();
-        toBuys.setUser(user);
-        toBuys.setStuff(stuff);
-        toBuys.setAmount(toBuyDTO.getAmount());
-        toBuys.setStore(toBuyDTO.getShop());
+        Optional<ToBuys> existingToBuy = toBuysRepository.findByUserAndStuff(user, stuff);
 
-        // データベースに保存
-        return toBuysRepository.save(toBuys);
+        if (existingToBuy.isPresent()) {
+            // 存在する場合は数量を更新
+            ToBuys existing = existingToBuy.get();
+            existing.setAmount(existing.getAmount() + toBuyDTO.getAmount());
+            return toBuysRepository.save(existing);
+        } else {
+            // 新しい材料を作成
+            ToBuys toBuys = new ToBuys();
+            toBuys.setUser(user);
+            toBuys.setStuff(stuff);
+            toBuys.setAmount(toBuyDTO.getAmount());
+            toBuys.setStore(toBuyDTO.getShop());
+            return toBuysRepository.save(toBuys);
+        }
 
     }
 
@@ -212,7 +220,7 @@ public class ToBuysService {
      * @param authentication 認証情報
      * @return 追加された「買うもの」のリスト
      */
-    public List<ToBuyResponseDTO> addByRecipeId(Long recipeId, Authentication authentication) {
+    public List<ToBuyResponseDTO> addByRecipeId(Long recipeId, Long servings,Authentication authentication) {
         // ユーザー情報を取得
         String username = authentication.getName();
         User user = userRepository.findByUsername(username)
@@ -225,7 +233,9 @@ public class ToBuysService {
 
         for (RecipeStuffs rs : recipeStuffsList) {
             Stuffs stuff = rs.getStuff();
-            int requiredAmount = rs.getAmount();
+            
+            // 材料の数量をサービング数に基づいて計算
+            int requiredAmount = rs.getAmount() * (servings != null ? servings.intValue() : 1);
 
             Optional<ToBuys> existingToBuyOpt = toBuysRepository.findByUserAndStuff(user, stuff);
 
diff --git a/frontend/src/pages/StockPage.tsx b/frontend/src/pages/StockPage.tsx
index 47603c9..b359f94 100644
--- a/frontend/src/pages/StockPage.tsx
+++ b/frontend/src/pages/StockPage.tsx
@@ -39,6 +39,14 @@ const formatDateLocal = (date: Date) => {
   return `${year}-${month}-${day}`;
 };
 
+// 日付をyyyy-MM-dd形式で返す関数
+const formatDateLocal = (date: Date) => {
+  const year = date.getFullYear();
+  const month = (date.getMonth() + 1).toString().padStart(2, '0');
+  const day = date.getDate().toString().padStart(2, '0');
+  return `${year}-${month}-${day}`;
+};
+
 // 新規在庫の初期状態
 const EMPTY_STOCK: Omit<Stock, 'stockId' | 'stuffId'> & { stuffId: number | null } & { newAddition: boolean } = {
   stuffId: null,