PURPOSE: To obtain a motor which is compact and has a high frequency noise by providing a magnet at one end of a rotor and providing a metal plate between the magnet and the rotor.

CONSTITUTION: A substrate 12 is attached to the end of a supporting plate 11 attached to the inner surface of the peripheral wall of a motor case 1. A Hall element 13 for detecting the rotation of a motor is attached to a position facing the peripheral edge of the magnet 8 of the substrate 12. When the motor is operated, a metal plate 7 and the magnet 8 are rotated together with a rotor 3. A magnetism received by the element 13 from the magnet 8 is varied by the rotation of the magnet 8, and the element 13 detects the rotations of a rotary shaft 4 and the rotor 3 from the variation of the magnetism. A magnetic flux generated in the direction of the magnet 8 from a coil 2 and a magnetic flux generated in the direction of the coil 2 from the magnet 8 are absorbed to the plate 7 at the time of operating the motor. Since the rotation detector is mounted in a motor case 1, the motor becomes compact.