Patent ID: 7423357

Claim:
An electric rotating machine comprising: a magnet rotor which has a rotor yoke formed with ferromagnetic materials and comprising a magnet attachment surface extending in a peripheral direction, and a plurality of permanent magnets for constituting a magnetic field which are intermittently arranged in the peripheral direction of said rotor yoke and are attached on said magnet attachment surface; and a stator which has an armature core including magnetic pole portions opposed to magnetic poles of said magnet rotor and an armature coil or coils wound around said armature core, wherein: a series of grooves each of which has a v-shaped section and extends around a peripheral surface of said rotor yoke is provided on said magnet attachment surface of the rotor yoke, said grooves being arranged in an axial direction of said rotor yoke without having spaces therebetween, a flat surface is formed on said magnet attachment surface by filling up the grooves with metal or resin at a portion where each permanent magnet is supposed to be attached to attach each magnet to each flat surface.