A driving device of a capacitive load includes a modulator that executes
pulse modulation on a drive waveform signal. An inductor performs
low-pass filtering on the modulated drive waveform signal and outputs the
low-pass filtered signal as a drive signal towards a load capacitor as
the capacitive load. A load selection control circuit selects a load
capacitor and a dummy load capacitor to be connected to the inductor so
that a sum of the capacitances of the selected load capacitor and dummy
load capacitor is kept within a predetermined range. A feedback circuit
executes a filtering process on the drive signal so that a frequency
characteristic of a passing band of the drive signal becomes
substantially flat. The resulting signal is provided to the modulator as
a feedback signal. The modulator executes the pulse modulation on a
difference value between the drive waveform signal and the feedback
signal.