PURPOSE: To perfectly remove the core sand even if the time of chipping treatment is short by executing the sand removal in the core with shot blast using the sand after executing the chipping treatment applying vibration to a casting.

CONSTITUTION: In the core sand removal separating and removing the core sand in an intake manifold cast product W, after executing the chipping treatment applying the vibration to the cast product W with a chipping hammer P, the shot blast is executed through nozzles N by using the sand as an injecting material. By this method, the core sand is perfectly removed even from the bending hole 1 and the casting flash is effectively removed, too. Since the chipping can be good in such short time as about 3-10sec, the load of the worker is light, and since the injecting material uses the sand, the treatment without damaging to the casting surface can be executed in the low cost.