To obtain stable motor rotation by applying a sufficient pre-load to a bearing, and furthermore, by applying a side load to a rotor even if it is a thin motor.

An arc-shaped auxiliary magnet 34, consisting of a ferrite-family rubber magnet, is provided at a recessed place 33 of a support member 23 so that the clearance between the auxiliary magnet 34 and the lower surface of a rotor yoke 29 is set to a prescribed value and is positioned immediately outside an outer wheel 26a of a ball bearing 26, the rotor yoke 29 consisting of a magnetic material is subjected to magnetic attraction by the magnetic force of the auxiliary magnet 34, and pre-load is applied to the ball bearing 26 downward in the axial direction. Also, the arc-shaped auxiliary magnet 34 applies press (side load) to a rotor in a radial direction.