PURPOSE: To evenly and sharply finish the edge part of a cooling knife chip by bonding an abrasive paper sheet to the upper face of a sponge to give the cushioning characteristics to the abrasive surface.

CONSTITUTION: A rectangular abrasive paper sheet 1 is bonded to the upper face of a sponge body 2 to give the cushioning characteristics to the abrasive surface A. This sponge body 2 having the abrasive surface A is mounted on an abrasive base 3 so that with the edge part of a cooking knife in flexible contact with the abrasive surface A to maintain the stable abrasive friction, the entire edge part of the cooking knife is polished sharply evenly.