Ink is injected by means of manipulating the relative potential relationships of voltages applied to selected electrodes, nonselected electrodes and an opposed electrode 20 among a plurality of record electrodes 13a through 13z installed at vicinities of an opening portion 11 of a head. Thus, printing of high resolution is made possible and by using a dispersing type ink and changing polarities of the voltages applied to the opposed electrode 20 and the record electrodes, the density of injected ink is made variable. <IMAGE>
