PURPOSE: To improve workability to a large extent, in a voltage control type printing head, by easily controlling and converting drive voltage corresponding to the input value of a D/A converter by operation only inputting the control value of driving voltage composed of digital data through the D/A converter.

CONSTITUTION: A control value composed of digital data of driving voltage/ current conversion is inputted to D/A converter through an amplifying circuit of operational amplifiers 01 - 04 and resistors. In this D/A converter 20, predetermined integration processing is performed to an introduced reference current corresponding to said input value to output the processing result from an output terminal (OUT). Further, current/voltage conversion is performed in a circuit of succeeding operational amplifiers 05, 06 and resistors R12, VR3 to set the driving voltage of a printing head corresponding to the above mentioned integrated value.