<p>[PROBLEMS] To sufficiently prevent generation of migration and finely control strokes of a piezoelectric element. [MEANS FOR SOLVING PROBLEMS] A boost switching circuit (5) increases a power supply voltage and applies the voltage to a piezoelectric element (4). A step-down switching circuit (7) generates a negative voltage from the power supply voltage and applies the negative voltage to the piezoelectric element (4). A switching element (S1) closes and connects the piezoelectric element (4) to the GND. A switching element (S2) closes and connects the piezoelectric element (4) to a power supply. A PWM control circuit (9) varies duty ratios and inputs PWM control signals to the boost switching circuit (5) and the step-down switching circuit (7), respectively. A control device (10) controls the duty ratio of the PWM control signal by the PWM control circuit (9), and also controls opening/closing of the switching elements (S1, S2).</p>
