PURPOSE: To provide a high precision piezoelectric transformer driving circuit with which the constant output voltage of the piezoelectric transformer which does not depend upon temperature is obtained.

CONSTITUTION: A detected voltage (feedback signal) which is obtained from a partial electrode 4 on the piezoelectric ceramic rectangular plate 1 of a piezoelectric transducer is inputted to a phase shift circuit 8 through a feedback signal detector 7. The output of the phase shift circuit 8 is inputted to the input terminal 13 of a temperature compensator 15 through a pushpull circuit 9 and the output terminal 14 of the temperature compensator 15 is connected to a driving electrode 3 on the piezoelectric transducer. If the feedback signal of the piezoelectric transducer is varied by a temperature, the driving voltage has to be varied so as to correct the variation of the feedback signal. Therefore, the constants of the thermistor, the resistor connected in series to the thermistor and the resistor connected in parallel to the thermistor in the temperature compensator are properly selected to give an arbitrary temperature variation to the resistance value of the temperature compensator 15.