PURPOSE: To protect the surface of a permanent magnet and to facilitate fixing of a balance weight by molding a rotor core and a permanent magnet arranged on the surface thereof with a nonmagnetic material.

CONSTITUTION: A rotor is constituted by fitting, a rotor core 2 on a motor shaft 1, securing a plurality of permanent magnets 3 constituting poles onto the surface of the rotor core 2, and then molding the rotor core 2 and the permanent magnets 3 entirely with a nonmagnetic molding material 4. When they are molded, protrusions 6 for correcting imbalance of the rotor and a notch 5 indicating a magnitization switching point are formed simultaneously. Since the molding material is bonded onto the outer peripheral surface of the permanent magnets, the outer peripheral surface of the permanent magnet is protected. Furthermore, the imbalance correcting protrusion facilitates fixing of a balance weight at the time of imbalance correction. The permanent magnet, which can not be seen from the outside, can be aligned accurately by means of the notch for indicating the magnetization switching point.