By ejecting pressurized ink from a nozzle, ink droplets are produced and shoot toward a recording paper to be deposited thereon. In order to produce a recording pattern by correspondingly deflecting the ink droplets, the latter is charged in dependence upon the recording information signal. The ink droplets thus charged are then subjected to a coulomb force upon passage through a deflection electric field. For the purpose of charging the ink droplets properly by means of synchronizing the information signal precisely with the timing phase of the ink droplets production, the magnitude of voltage supplied to an electro-strain element for vibrating the nozzle is controlled.