PURPOSE: To prevent a machining defective, peripheral sagging or the like from occurring in a clutch, etc., by forming a dynamic pressure generating surface which makes up an abrasive layer between a machining surface and a polisher, in case of the polisher of a polyester fiber, etc., for mirror finishing of a silicon wafer or the like.

CONSTITUTION: A polisher 1 which sticks a polyurethane foaming layer on a polyester fiber layer is stuck to a rotary surface plate 2 in a flatness of about 2W3μm, while a correction ring 6 making up a projection of about 5W10μm in height is set up on the circumferential part, and the surface plate is rotated. With this rotation, a lot of grooves 7 having a tilt angle of about 0W15° on the polisher surface are formed, and a dynamic pressure generating surface is thus constituted. With this constitution, any influence from the elastically deformed polisher on the peripheral part of a wafer is eliminated so that flatness is improvable.