The inner wall of a hub has a step surface between an upper bearing mounting surface and a magnet mounting surface. A spacer of ring-like shape is directly mounted to the step surface of the hub for determining the upper position of a rotor magnet. The inside diameter of the spacer is smaller than the inner wall at the bearing mounting surface of the hub so that a space is created between the bearing mounting surface, the spacer, and the bearing for holding a portion of adhesive. When a portion of the adhesive applied for bonding the bearing to the bearing mounting surface of the hub remains uncured, it will be retained in the space and prevented from entering the interior of the motor.