PURPOSE: To improve the reliability of rotary operation, insulation or voltage withstandability at a rotor section and to reduce the diameter and the thickness by containing upper and lower insulating holding rings in a motor case and holding the outer circumferential edge of a flat stator section mounting a motor coil by means of the holding rings.

CONSTITUTION: The outer circumferential edge section of a flat stator section 3 mounting a motor coil is supported from below by the step section 11a of a mold ring 11 and held from above by the lower end face of a stopper ring 12 through pressing of an upper motor case 10, thus holding the motor coil in the gap between a magnet 1 and a rotary yoke 4.