PURPOSE: To prevent mutual superposition of works and a strong gouge from being caused, by performing the polishing of a work in a polishing tank composed so that the length more than 1.3 times the diameter of the polishing tank.

CONSTITUTION: On rotation of a driving side rotating body 1 to the right, the driven side rotating body 3 of a polishing tank 2 is rotated in the same direction as that of a driving side rotating body 1 via two intermediate rotating bodies 4/4a. While both driving side rotating bodies 1/3 are rotated to the right the intermediate rotating body 4 is closely fitted to both sides rotating bodies l/3, but when the driving side rotating body 1 is changed to a reverse rotation (the left rotation), the right intermediate rotating body 4a is sticked to both driving side rotating bodies 1/3, so the rotation of the driving side rotating body 1 is correctly transmitted to the driven side with an unreasonable load being not applied on the intermediate rotating body 4 without wastefulness.