To attain simple control and improve motor efficiency by forming at least eight salient poles at the outer periphery edge of a rotor for making inductive voltage induced to an exciting coil approximate to a sinewave including little ripple, so as to detect the rotating position and the rotational speed of the rotor accurately.

A stator 3 is formed with 6 magnetic pole iron cores 7 around which an exciting coil 9 is wound. A rotor 21 is formed with eight salient poles, and a slot is formed at the respective salient poles to insert a permanent magnet 29. The exciting coil 9 of the stator 3 is passed through most of magnetic force lines, which is from the N-pole to the S-pole of the permanent magnet 29 of the rotor 21, and its one part is guided to the permanent magnets 29 which are adjacent to each other. It is thus possible to obtain inductive decompression which includes almost no ripple and is approximate to a sinewave in the exciting coil 9, therefore, the rotating position of the rotor 21 can be detected through inductive voltage with 81 stable waveform, thus it is possible to improve control performance and motor efficiency.