PURPOSE: To suppress generation of a cut by making it possible to process rare earth magnets individually, in a chamfering of rare earth magnets.

CONSTITUTION: In a processing method to process both surfaces of a work 3, in which plural grindstones 10 are provided opposing their processing surfaces each other, and the work 3 is held and inserted by a carrier 2 between the opposing surfaces of the grindstones 10, each grindstone 10 is made by fixing a rubber 7 in which grinding stones 8 are buried on a grindstone base metal 1, and a rare earth magnet is chamfered by the free displacement of the grinding stones 10 by a grinding resistance.