An improved ink-jet printer of the so-called current flow type wherein a current is passed through a conductive ink contained between a pair of electrodes so as to cause the ink to become vaporized and cause trapped gasses or bubbles to expand suddenly, exerting a sufficient pressure upon the ink to force a droplet of ink from a nozzle is disclosed, wherein at least one projection of electrically insulating material is disposed between the pair of electrode for increasing the density of the current at a position directly below a nozzle. With the projection thus provided, only a limited portion of the conductive ink participates in the generation of heat, and boiling of the conductive ink takes place only at the position directly below the nozzle. Accordingly, droplets of conductive ink are produced with minimum power consumption and can be ejected in a uniform direction. The position where boiling of the conductive ink takes place is remote from the electrodes, so that the electrodes are substantially free from cavitation and thermal shock and, hence, they have a long life span.