To obtain acid resistance and at the same time strong bonding strength in a permanent magnet assembly formed by fixedly bonding a rare earth permanent magnet to a body such as another magnet, a yoke, a reinforcement material or the like with a bonding magnet.

A rare earth permanent magnet 11a and a rare earth permanent magnet 11b are fixedly bonded by an electrically conductive bonding agent 13 in advance and after that, further, the surface of a permanent magnet assembly is coated with an electrically conductive agent 17, and the surface of the electrically conducive agent 17 is covered with an acid resistance plating layer 12 by electroplating, thereby to efficiently make the most of the primary properties of a bonding agent, to obtain strong bonding strength and at the same time to realize acid resistance required for an acid resistance plating layer with which the peripheral surface of a permanent magnet assembly is finally covered.