A piezoelectric actuator apparatus which is connectable to a power supply includes: a piezoelectric actuator which is provided with a plurality of piezoelectric elements each of which is sandwiched by two types of electrodes; a drive device which is connected to the power supply to drive each of the piezoelectric elements by changing a voltage between the two types of electrodes; a comparison section which compares a predetermined reference value with one of a supply voltage from the power supply to the drive device and an electric current flowing between the power supply and the drive device under the condition that the drive device applies the voltage to at least one piezoelectric element of the piezoelectric elements; and a judgement section which judges a degradation degree of dielectric strength voltage for the at least one piezoelectric element based on a comparison by the comparison section.