PURPOSE: To decrease the jitter of a rotor by fixing the rotor directly to one side of a rotary shaft, which is supported by the bearing arranged at a common base, and fixing the rotor of a motor to the other side through adhesive substance so as to enlarge the phase delay.

CONSTITUTION: A rotary shaft 3 is supported freely in rotation by a bearing (omitted form the figure) provided inside a common base 1. A rotor 2 is fixed directly to one side of the rotary shaft 3. On the other side of the rotary shaft 3, a rotor R consisting of a rotor yoke 5 and a permanent magnet 6 is fixed by screws through shock absorbing material consisting of adhesive substance 11 and a metallic plate 12 to the boss 4 of the rotary shaft. The rotor R forms U shape and covers a stator S consisting of a stator core 7 and stator winding 8. Hereby, the path of rotation transmitted from the rotor R is divided in two, and for the path transmitted through the shock absorbing material, the phase delay becomes large, and the jitter of the rotor is reduced.