PURPOSE: To effect shot blasting for inner and outer surfaces of a workpiece on a workpiece receiving device with a same shot blasting device by a method wherein an inner shot blasting device is connected to an outer hanger conveyor at a ceiling position enabling a movement of a shot blasting chamber, and the inner shot blasting, device is ascended or descended at a next position.
CONSTITUTION: A workpiece 60 is transferred to a shot blasting chamber 1 by a hook 18 of a hanger conveyor 6 cooperatively connected to an outer hanging conveyor at a first position of a ceiling member 5 shown, the workpiece 60 descended by a distance H 2 along with the hanging conveyor 6 is placed on a receiving device 54 and an outer surface shot blasting is performed by a shot projection device 3 while being applied with a rotational movement. Then, the ceiling member 5 is lifted up on a lifting device by a distance H 1 and thereafter moved rearwardly by a distance a A toward a second side position. An inner shot blasting device 7 aligned with the workpiece 60 is descended and shot blasting for an inner surface of the workpiece 60 is effected by an impeller unit 30. In this way, shot blasting for both or one of the inner and outer surfaces of the workpiece may be selectively effected with one shot blasting device.