An ink jet printer has a plurality of ink ejection electrodes (106) for receiving an ejecting voltage to eject an ink droplet, a pulse width generator (14) for specifying the pulse width of each ejecting electrode (106) to obtain a dot diameter of the ink droplet for gray-scale printing. The ejecting voltage Vej for each ejection electrode (106) is divided into a plurality of unit pulses. Each unit pulse is supplied to a corresponding ejection electrode (106) concurrently with unit pulses for other ejection electrodes (106). A combination of unit pulses for a single ejection electrode (106) forms a single ink droplet having a dot diameter based on the number of unit pulses, thereby achieving accurate gray-scale printing with a reduced circuit scale. <IMAGE>
