PURPOSE: To screen polishing objects and objects to be polished automatically by dividing the base ends of first and second tube bodies by an inclined plate installed in an inner tube and forming multiple screening holes of a proper diameter on the outer periphery of the second tube body.

CONSTITUTION: Polishing objects 35 and objects to be polished 36 in a polishing chamber 3 are taken from a first intake 11, and transferred into a screening tube 21 by the guide of an inclined plate 15. Next, the objects of small diameter 35 are dropped through the sorting holes 16 of the screening tube section 25 into a screening chamber 4, and the objects to be polished of larger diameter 36 are transferred through the screening holes 16 to a spiral 28 of a screening tube section 25 and taken out to the outside of an outer tube 1. In addition, the polishing objects 35 dropped through the screening holes 16 of the screening tube section 25 into the screening chamber 4 are taken in from a second intake 12 by the rotation of the outer tube 1 and dropped into the polishing chamber 4.