diff --git a/my_Tetris.py b/my_Tetris.py
index 6043cec..4e95ce0 100644
--- a/my_Tetris.py
+++ b/my_Tetris.py
@@ -58,6 +58,8 @@ def check(center):
         if cube[0] < 1 or cube[1] < 1 or cube[0] > grid_num_height \
                 or cube[1] >grid_num_width:
             return False
+        if num_list[cube[0]-1][cube[1]-1] != 0:
+            return False
 
 while True:
     for event in pygame.event.get():