--- a/pallets/nft/src/lib.rs
+++ b/pallets/nft/src/lib.rs
@@ -280,6 +280,10 @@
 			}
 			<ItemList<T>>::remove((collection_id, item_id));
 
+			// update balance
+			let new_balance = <Balance<T>>::get((collection_id, item.owner.clone())) - 1;
+			<Balance<T>>::insert((collection_id, item.owner.clone()), new_balance);
+
 			Ok(())
 		}
 
@@ -308,10 +312,19 @@
 			}
 			<ItemList<T>>::remove((collection_id, item_id));
 
+			// update balance
+			let balance_old_owner = <Balance<T>>::get((collection_id, item.owner.clone())) - 1;
+			<Balance<T>>::insert((collection_id, item.owner.clone()), balance_old_owner);
+
+			let balance_new_owner = <Balance<T>>::get((collection_id, new_owner.clone())) + 1;
+			<Balance<T>>::insert((collection_id, new_owner.clone()), balance_new_owner);
+
 			// change owner
 			item.owner = new_owner;
 			<ItemList<T>>::insert((collection_id, item_id), item);
 
+
+
 			Ok(())
 		}
 	}
--- a/pallets/nft/src/tests.rs
+++ b/pallets/nft/src/tests.rs
@@ -68,6 +68,8 @@
         // burn item
         assert_ok!(TemplateModule::burn_item(origin1.clone(), 1, 1));
         assert_noop!(TemplateModule::burn_item(origin1.clone(), 1, 1), "Item does not exists");
+
+        assert_eq!(TemplateModule::balance_count((1, 1)), 0);
 	});
 }
 
@@ -176,5 +178,9 @@
         // transfer
         assert_ok!(TemplateModule::transfer(origin1.clone(), 1, 1, 2));
         assert_eq!(TemplateModule::item_id((1,1)).owner, 2);
+
+        // balance_of check
+        assert_eq!(TemplateModule::balance_count((1, 1)), 0);
+        assert_eq!(TemplateModule::balance_count((1, 2)), 1);
         });
 }