To prevent a base from being vibrated by providing the base with a driving device for moving a pair of polishing members in reciprocal directions.

A pair of polishing members 4, 5 of the same mass are reciprocated and a part of a blade of a material 21 to be polished is pressed to the edge of a support part 2 for a material to be polished to press a knife edge to the polishing members 4, 5 with uniform pressure, and with the knife edge laid along a guide roller 20, the material 21 to be polished is moved to uniformly polish the knife edge. Thus, the material 21 to be polished is polished and the polishing members 4, 5 are reciprocated in the reciprocal directions through driving pins 18, 19 by a driving motor, so that vibration is not produced from the base 1 of the polishing device, and the same knife edge polishing angle θis kept to achieve good finish even by an amateur, and further the knife edge part can be smoothly moved along the guide roller so as to prevent biased polishing without skill.