Ultrasonic motors possess many advantages, such as high torque, low speed, compact size, and no magnetic field generation; however, there are several technical problems to be solved. Improvement of efficiency is important from a low power drive view point. The purpose of this work is to achieve maximum efficient drive of ultrasonic motor. Firstly, this paper shows characteristics based on efficiency of ultrasonic motor and proposes a search method of maximum efficiency point. Furthermore, this paper presents a speed control method of the motor by PWM control of DC source combined with drive frequency control in order to realize maximum efficient drive.