PURPOSE: To facilitate polishing of only one part of a plane and of a narrow groove or the like in a magnetic workpiece enabling its pressed force to be easily controlled by connecting a polishing material, connected by a binding agent, to a magnetic unit material.

CONSTITUTION: Providing a magnetic workpiece 5 to be arranged between magnetic poles 7 and 8, a polishing material 3a, connected by a binding agent 3b, is connected to a magnetic unit material 4 forming a plate-shaped magnetic polishing unit 1, and its surface of the polishing material 3a is adapted to a machined surface of the magnetic workpiece 5. Next allowing an electric current to flow in a coil 11 from a power source 12 generating a magnetic field between the magnetic poles 7 and 8, the magnetic polishing unit 1 is attracted to and forced to come into press contact with the workpiece 5 by magnetizing it while the magnetic unit 4 of the magnetic polishing unit 1 on the workpiece 5. By this attracting force, a surface of a layer 3 of the polishing material 3a and the binding agent 3b is pressed to the workpiece 5, and under this condition, relatively moving the magnetic polishing unit 1 sliding on the workpiece 5, its surface is polished. Here the attracting force (that is, polishing pressure) is controlled in its intensity by controlling a flow value of the current in the coil 11.