PURPOSE: To maintain a constant press force per an unit area between a sheet- like grinding wheel and a workpiece and improve polishing accuracy by providing said grinding wheel exposed to the side contacting the workpiece and a permanent magnet in a position spaced somewhat from the surface contacting with the workpiece to generate magnetic lines of force perpendicular to the transfer direction of a magnetic polishing tool.

CONSTITUTION: A sheet-like grinding wheel 7 is pressed against the surface of a workpiece 10 with a predetermined press force on the basis of an adsorbing force generated between permanent magnets 3, 4, 5 of a magnetic polishing tool and the workpiece 10 of magnetic material and under such condition reciprocated to the workpiece 10. Thus, said grinding wheel 7 polishes the surface of the workpiece 10 without any undulation while maintaining the press per an unit are constant. Further, the whole polishing tool becomes so thin that even the inner surfaces of a narrow groove can be polished easily with high accuracy.