PURPOSE: To achieve highly efficient rotary driving, by vibrating a vibration chip having first and second pawl portions contactable respectively with two interlocked rotors through expanding/shrinking function of a piezoelectric element.

CONSTITUTION: A piezoelectric actuator is provided with a C-shaped vibration chip 11 and a laminated piezoelectric element 12 is jointed between one and the other arms 11a, 11b thereof. First and second V-shaped pawl portions 11a∼11c pointing the elongating direction of the piezoelectric element 12 are formed at the tip of respective arms of the vibration chip 11 and displaced through vibration of respective arms. Drum type rotors 14, 15 arranged rotatably around supporting shafts 16, 17 are engaged with respective gears 18, 19 and interlocked each other. When two arms 11a, 11b of the vibration chip 11 are vibrated through expansion/shrinkage of the piezoelectric element 12, respective rotors 14, 15 are rotated through the first and second pawls 11c, 11d to produce rotary driving power through one or both rotors 14, 15.