PURPOSE: To suppress primary and secondary resonance peaks to low and to improve vibrating characteristics of a piezoelectric actuator by separating a control electrode of a bimorph type piezoelectric element of the actuator into a main electrode, an auxiliary electrode and a sensor electrode.

CONSTITUTION: An electrode 41 of a bimorph type piezoelectric element 31 is formed of a pair of main electrode 43 and a subelectrode 45 and a sensor electrode 47 independent from each other. The electrode 43 is relatively narrowed at parts corresponding to antinodes of primary and secondary resonances to be formed with narrowed parts 43a. On the other hand, the electrode 45 is, on the contrary, widened in an electrode pattern at parts corresponding to the antinodes of primary and secondary resonances to be formed with wide parts 45a. The electrode 47 is formed longitudinally in a uniform width to detect generation of a resonance peak. The electrode 45 is driven in a reverse phase to the electrode 43 with frequency components of the primary and secondary resonances from the electrode 45 as drive signals of the electrode 45 by using the electrode 45 formed with the wide parts 45a at the parts corresponding to the antinodes of the resonances to suppress the resonance peak to a low value.