PURPOSE: To simplify the driving circuit of a thermal head and to obtain a recording data with high quality by conducting entirely digitally the control of conduction time to a heating resistor.

CONSTITUTION: A prescribed data is stored in shift registers 31∼332. In opening gate drivers 21∼232 from this state by bringing an enable selecting terminal 11 to "1" level, a signal for one bit's share is transmitted from the shift registers 31∼332, an output of the gate drivers 21∼232 goes respectively "0" or "1" level, and the heating resistor corresponding to the gate driver having "1" level output is heated. After a fixed time to the start of transmission of the "1" level signal to this enable terminal 11, a clock pulse is transmitted from a clock terminal 12 to update the content of the shift registers 31∼332 by 1-bit, the result is outputted and only the heating resistor corresponding to the gate driver having "1" level output is conducted and heated.