PURPOSE: To unify the quantity of ink discharge from all nozzles and enable the printing quality to be improved and deterioration to be prevented by providing an applied energy correction part for correcting energy applied to the element on the basis of each resistance value of heat resistance elements detected at a resistance value detection part.

CONSTITUTION: When respective resistance values of all heat resistance elements 1a-1n are detected, CPU 22 serves to set respective electrification times of the resistance elements 1a-1n by setting electrification time data corresponding to each resistance value in a correction pulse calculation circuit 33. Next, the printing data outputted from CPU 22 is corrected by the electrification time from the correction pulses calculation circuit 33 at a data processing unit 30 and fed to the resistance elements 1a-1n and, accordingly, the resistance elements 1a-1n are electrified only for the time corresponding to each resistance value. In this way, fluctuation in the resistance value of the resistance elements 1a-1n is corrected by the electrification time relative to each heat resistance elements, in order that the quantity of ink discharge from all nozzles becomes uniform with the result that printing quality is improved.