A position where the projection member is disposed is optimized by the product of a vibration displacement distribution of a vibration member composed of an elastic member for exciting the primary elastic progressive waves or more in the radial direction and the tertiary elastic progressive waves or more in the peripheral direction, and a generation force distribution of a vibration member to be caused in accordance with the pressure force so that the motor output is made larger. The construction is optional in accordance with the necessary characteristics, and the characteristics are superior by the shape of the supporting means of the vibrating member and the vibration member, thus providing an ultrasonic motor of higher stability.
