diff --git a/WebApi_data_value/Services/BackgroundService.cs b/WebApi_data_value/Services/BackgroundService.cs
index 5489451..f870e0d 100644
--- a/WebApi_data_value/Services/BackgroundService.cs
+++ b/WebApi_data_value/Services/BackgroundService.cs
@@ -66,7 +66,7 @@ public class ParkingUpdateService : BackgroundService
                             {
                                 Timestamp = DateTime.Now,
                                 TotalParkingSpaces = totalParkingSpaces,
-                                RemainingSpaces = remainingSpaces,
+                                RemainingSpaces = Math.Max(remainingSpaces, 0),  // 確保儲存時不為負數
                                 MonthlyRentSpaces = monthlyRentNumber,
                                 TemporaryRentSpaces = Math.Abs(temporaryRentNumber),
                                 DayOfWeek = DateTime.Now.ToString("dddd", new CultureInfo("zh-TW"))