PURPOSE: To realize a piezo-electric type print head driving circuit which eliminates impact action unnecessary for a wire by discharging a piezo-electric body after electric charge is accumulated therein when a voltage is applied thereto for driving.

CONSTITUTION: When an impact signal Vb for driving a piezo-electric body P mores to H, transistors Q2 and Q1 are caused to conduct successively. At this point, as a short-circuit signal Vc is L, a transistor Q3 is turned OFF and a voltage Vd roughly equal to a power source voltage Va develops at a terminal 8. When the signal Vb moves to L, the transistors Q2 and Q1 are turned OFF successively. At this point, the short-circuit signal Vc goes to H, which turns the transistor Q3 ON to have a terminal 8 grounded, so that the voltage Vd is roughly zero. In orther words, distortion caused in the piezo-electric body P by the impact signal Vb is expansively transmitted to drive a wire. When the short- circuit signal Vc goes to H, the wire of the print head is returned. here, in order to prevent impact action unnecessary for the wire, the time T for applying a voltage Eh to the piezo-electric body is set at a value less than the cycle of free vibration of the wire.