The aim of this research is to evaluate the driving performance of a micro ultrasonic motor, 1.8mm in casing diameter. The micro ultrasonic motor is driven by a cylindrical piezoelectric vibrator, 0.8mm in diameter. A laser surface velocimeter, an electric balance and an xyz micro stage were used for the evaluation of the relationship between the preload, the revolution speed, and the applied voltage. By using another vibration mode which had a contact with outer edge of vibrator, lager output torque was obtained. When the frequency was 314.5kHz, the applied voltage was 35V_<P-P> and the preload was 2.0mN, the maximum revolution speed was 9.1×10^3rpm and starting torque was 5.5μNm.