PURPOSE: To polish a work in high efficiency without deteriorating surface roughness of the work, by mixing the work to media in a barrel tank, applying rough polishing at a high rotary speed and then performing finish polishing at a low rotary speed.

CONSTITUTION: A shaft 8 is fixedly provided to a rotary bottom part 6 in a barrel tank, and a V-pulley 10 is fixed to the point end of the shaft 8. The pulley 10 is coupled to a DC motor 12 through a V-pulley 14 and V-belt 16, and the bottom part 6 is driven by the motor 12. A controller 18 successively feeds a rotary command signal SN of the motor 12 to a motor driver circuit 20 in accordance with a predetermined program. A rough polishing rotary signal is fed to the circuit 20 from the controller 18 in accordance with the predetermined program, and the bottom part 6 is driven to perform polishing. Then a finish polishing rotary signal is fed to the circuit 20, and the bottom part 6 is driven rotating to perform finish polishing.