Using the extensional vibration mode of a PZT ring, an ultrasonic rotary motor is successfully made. The PZT ring is radially polarized and acts as a stator of a motor. The traveling wave along the circumference of the ring is obtained by driving two standing waves which are temporally and spatially phase shifted by 90 degrees from each other. A structure similar to a drum brake is employed as a rotor. The maximum torque and maximum efficiency of the motor are 200 g·cm and 1.9%, respectively.