PURPOSE: To controllingly drive each bit without requiring any means for controlling impressed energy for each bit as a unit, by controlling driving energy for each heating element with the length of data corresponding to each heating element as a pulse width of a driving pulse.

CONSTITUTION: Outputs from QA and QC terminals of a shift register 4 are inputted respectively to pins 3, 4 of an ROM8, while information on the temperature of a head substrate is inputted to pins 5, 6, 7 of the ROM8. In accordance with the eight inputs to the ROM8, the width of an impressed pulse for each bit is determined by using a table stored in the ROM8. This operation is conducted in the first of 8 transfer operations. Therefore, all the data are made to be True in the first transfer operation. One of 8 bits in the ROM8 is selected in accordance with the number of times of transfer operations, is inputted into a gate 5, and an output from the gate 5 is inputted into a shift register 12. The data transferred by the n-th transfer operation are latched by a head, and the signal of the data is recorded until the next LOAD signal is inputted. When the eighth latching operation is completed, the data latched are reset, and recording in one line is completed.