PURPOSE: To always push a polishing brush with a constant polishing pressure in response to each thickness, even if patches having different thickness are mixed, to enable the stabilized good polishing by providing polishing rolls to be energized to a supporting roll side with a predetermined force balanced with a connected balance weight.

CONSTITUTION: The top surface side of a patch to be carried by a pair of feeding rollers, 11 is polished by a first pair of polishing rolls 20F, and next, the lower surface side of the patch is polished by a second pair of polishing rolls 20R. At this time of polishing, a brush roll is elevated by a weight 33 in response to change of thickness of the patch, and while is made to abut on the patch with a constant pushing force independently from elevation thereof. Namely, the surface of the patch can be always polished with an appropriate polishing pressure. The brush roll is driven for rotation at a predetermined rotating number by a rotation driving motor 25, and while is driven for reciprocating movement in the axial direction thereof by an oscillation motor to perform polishing efficiently.