Abstract: An ultrasonic motor utilizing flexural travelling wave components. A ball bearing is constituted by the inner ring, the balls, and an outer ring provided with a groove similar to the ball positioning groove of the inner ring, at a position where the ball are interposed. A rotor is provided inside the amplifying projections which are formed in the vibration member. A coil spring is provided in order to bring the rotor and the projections of the vibration member into pressure contact with each other. A spring pressing seat having a groove for receiving the other end of the coil spring is fixed to the support pin, with the coil spring and the support pin centered. The coil spring receiving groove of the inner ring and the coil spring are positioned so as not to share the same vertical plane with the ball. In this manner the thickness of the ultrasonic motor can be reduced.