PURPOSE: To polish a screw with high accuracy even when the screw is of a complicated shape, by incorporating the screw into a barrel and filling viscous/ elastic abrasive grains thereinto, and alternately rotating the screw in the forward/backward direction while applying a pressure to those abrasive grains.

CONSTITUTION: A screw 1 is charged into a barrel 2 and viscous/elastic abrasive grains 6 are filled. The screw 1 is alternately rotated by a rotating means 5 in the forward/reverse direction while pressurizing those abrasive grains by a pressurizing means 4. Thereby, the viscous/elastic abrasive grains 6 are brought into pressure contact with the surface of the screw 1 to thereby frictionally polish the surface of the screw 1 by the abrasive grains 6.