PURPOSE: To finish the grinding process and plating film formation of a magnet material by one time of operation by a method wherein rare earth magnet material and small metallic balls are mixed with one another in a vessel, the surface of the rare earth magnet material is degreased in a basic cleaning solution while the vessel is being turned to be immersed and electroplated in an acidic zinc chloride plating-bath, using the rare earth magnetic material and the small metallic balls as a cathode as well as the plating-bath as an anode.

CONSTITUTION: The rare earth magnet material M is fed to a vessel 27 wherein multiple small metallic balls B are contained. The vessel 27 is immersed in a basic cleaning solution. The surface of the rare earth magnet M is degreased in degreasing vessel 2. Later, the vessel 27 is immersed in a washing vessel 3 to be washed. Next, the vessel 27 is pickled in a picking vessel 4 to be washed in another washing vessel 5. During these processes, the vessel 27 is being constantly turned at specific RPM by a moor 35 being driven. After grinding process such as chamfering corners, edges, etc., the vessel 27 is fed to a plating film formation vessel 6 to be electroplated using plating-bath as anode and the rare earth group magnet material M and the small balls B as cathode. In such a process, the plating-bath shall be the zinc chloride plating- bath.