PURPOSE: To improve shot effect against different shaped articles by forming grinding-cleaning material paths having different transfer widths on the front and back of a blade body.

CONSTITUTION: A front path 17a in a blade body 14 is shaped to differ from a back path 17b so that when various long products different in the width and size are subjected to shot blast, the products having different widths and sizes can be properly shot blased by rotaing forward and backward an impeller.