PURPOSE: To completely and quickly dissolve the clogging by abrasive grains of a pad for finishing the surface of a substrate for a magnetic disc into a mirror face.

CONSTITUTION: Three pieces of rotary brushes 2, wherein elements are bundled in pillar shape, are juxtaposed on a block-shaped holder 1, and each is rotated around its axis. At the same time, the holder 1 is reciprocated straight in longitudinal direction by a reciprocative diver. Upper and lower each top of the rotary brush 2 slides by the complicated motion based on reciprocative rectilinear drive and rotation, to the pad for finishing into a mirror face stuck to each surface of vertical opposition type of rotary surface plates not shown in the figure, whereby it removes abrasive grain clogging the surface of the pad, in short, dissolves the clogging. Furthermore, liquid discharge of abrasive grains is jetted out of the nozzle 3 attached to the holder 1 so as to support the dissolution of the clogging.