PURPOSE: To enable high speed recording at low signal voltage, by at least setting the min. pulse width Pw of signal voltage Vs to 1/fp<Pw<2/fp when the frequency of a recording picture element is set to fp and emitting ink by electrostatic force due to said signal voltage Vs.

CONSTITUTION: The clock pulse (a) determining the appearing cycle of a picture element has frequency fp and an image signal (b) is outputted in synchronous relation to the clock pulse and represented by 010101101110. The pulse width Pw of the wave form (c) of signal voltage Vs is larger by α (0<α<1/fp) than the pulse width 1/fp of the image signal (b) and the shape (d) of a dot is recorded by ink emitted by signal voltage Vs having the wave form (c). As shown by the wave form (c), if the pulse width Pw generating a blank between dots for the present, a recording condition having high recording picture element frequency can be selected with the long pulse width Pw without increasing signal voltage Vs.