A cup ring and a holding-plate are disposed at each side of a front bracket of a stator of a motor, to fix in place an outer ring of a front ball-bearing of the rotor of the motor in order to prevent creep between a bearing housing and the outer ring. A thickness of a bearing shim is adjusted such that a distance between an end portion of a tube section of the cup ring and a first end face of the outer ring is less than 0.1 mm. The holding plate is temporarily fixed to a given place of the motor shaft, and then screwed down thereto with a screw, so that the holding plate moves and solidly contacts the outer ring of the front ball bearing. An outer diameter of the motor shaft extending between the given place and the bearing is smaller than a center hole of the holding plate such that the holding plate does not contact the motor shaft.