<p>As an example, a rotor (1) includes rotor cores (1a to 1c) mutually coupled in the rotation axis Z direction. The rotor cores (1a to 1c) have identical configurations. The rotor core (1a) includes side surfaces parallel to the rotation axis (Z) and field magnets constituting a plurality of pole-faces different from one another by the number of pole pairs on the side surfaces and has uniform configuration in the rotation axis (Z) direction. The rotor cores (1a, 1b) forms a skew angle ?1 in the circumferential direction of the rotation axis (Z) while the rotor cores (1b, 1c) forms a skew angle?2. The skew angle? is decided by 360/(2pn) (p= the number of pole pairs; n: an integer greater than 1).</p>
