A potential supplied from a capacitive load drive unit to one end of a respective capacitive load is switched to an intermediate potential between a first and a second power supply potentials for a predetermined period of time prior to switching the potential of the one end of the capacitive load from the first to the second power supply potential, or vice versa, which minimizes charging and discharging currents of the load, variations of the potential supplied to the capacitive load, and hence power consumption involved, without providing a charging capacitor having a large capacitance in the capacitive load drive unit.