A liquid jet apparatus according to the present invention includes a drive waveform generator adapted to generate a drive waveform signal, a modulator adapted to execute pulse modulation on the drive waveform signal, a digital power amplifier adapted to power-amplify the modulated signal, on which the pulse modulation is executed by the modulator, with a pair of switching elements push-pull coupled with each other, a low pass filter adapted to smooth the amplified digital signal obtained by the power-amplification of the digital power amplifier, and a modulation period modification circuit adapted to modify a modulation period of the pulse modulation of the modulator based on data of the drive waveform signal.