diff --git a/backend/src/main/java/com/example/todoapp/controller/StocksController.java b/backend/src/main/java/com/example/todoapp/controller/StocksController.java
index 4ca9713..643473a 100644
--- a/backend/src/main/java/com/example/todoapp/controller/StocksController.java
+++ b/backend/src/main/java/com/example/todoapp/controller/StocksController.java
@@ -55,6 +55,14 @@ public class StocksController {
         List<StockResponseDTO> stockDTOs = stocks.stream()
                 .map(StockResponseDTO::fromEntity)
                 .collect(Collectors.toList());
+        
+        // //  Debug of calcAmountByStuffId
+        // var user = userRepository.findByUsername(authentication.getName()).get();
+        // for (var stock : stockDTOs) {
+        //     var amount = stockService.calcAmountByStuffId(user.getId(), stock.getStuffId());
+        //     System.out.println("\tAmount of " + stock.getStuffName() + ": " + amount);
+        // }
+            
         return ResponseEntity.ok(stockDTOs);
     }
 
diff --git a/backend/src/main/java/com/example/todoapp/repository/StocksRepository.java b/backend/src/main/java/com/example/todoapp/repository/StocksRepository.java
index 87d2cdd..e887b3e 100644
--- a/backend/src/main/java/com/example/todoapp/repository/StocksRepository.java
+++ b/backend/src/main/java/com/example/todoapp/repository/StocksRepository.java
@@ -94,4 +94,14 @@ public interface StocksRepository extends JpaRepository<Stocks, Long> {
      */
     List<Stocks> findStocksByUserIdAndStuff_StuffIdOrderByBuyDateDescStockIdDesc(Long userId, Long stuffId);
 
+    /**
+     * userId, stuffId を指定して，材料の総在庫数量を取得
+     *
+     * @param userId 検索するユーザーID
+     * @param stuffId 検索する材料ID
+     * @return 総在庫数量
+     */
+    @Query("SELECT SUM(s.amount) FROM Stocks s WHERE s.user.id = :userId AND s.stuff.stuffId = :stuffId")
+    Integer findAmountByStuffId(Long userId, Long stuffId);
+
 }
\ No newline at end of file
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 1be09d1..e97941f 100644
--- a/backend/src/main/java/com/example/todoapp/service/StocksService.java
+++ b/backend/src/main/java/com/example/todoapp/service/StocksService.java
@@ -146,5 +146,10 @@ public class StocksService {
         return userRepository.findByUsername(username)
                 .orElseThrow(() -> new UsernameNotFoundException(messageUtils.getMessage("error.auth.user.not.found.with.name", new Object[]{username})));
     }
+    
+    public int calcAmountByStuffId(Long userId, Long stuffId) {
+        Integer amount = stocksRepository.findAmountByStuffId(userId, stuffId);
+        return amount == null ? 0 : amount;
+    }
 
 }