A driving waveform has a first driving waveform (PLSTM1) composed of non-GND waveform, a second driving waveform (PLSTM2) composed of a non-GND waveform different from the first driving waveform, and a third driving waveform (PLSTM0) composed of a GND waveform, and a driving voltage V1 of the first driving waveform and a driving voltage V2 of the second driving waveform is |V1|>|V2|; and the driving circuit selects at least the first driving waveform and the second driving waveform or only the first driving waveform at every predetermined time in 1 pixel cycle in accordance with the discharge data, applies this to one of the two driving electrodes of the pressure generating unit and also applies only the second driving waveform to the other so as to operate the pressure generating unit by a differential waveform between the two driving electrodes.