A method of driving a piezoelectric actuator including: a piezoelectric element containing a piezoelectric body having coercive field points on a negative field side and a positive field side respectively and having asymmetrical bipolar polarization—electric field hysteresis characteristics in which an absolute value of a coercive electric field on the negative field side and a coercive electric field value on the positive field side are mutually different, and a pair of electrodes for applying voltage to the piezoelectric body; and a diaphragm which externally transmits, as displacement, distortion produced in the piezoelectric body when the voltage is applied to the piezoelectric body, includes the step of driving the piezoelectric actuator between a positive drive voltage and a negative drive voltage in a range not exceeding the coercive electric field, from among the positive and negative coercive electric fields, which has the larger absolute value.