A first counter electrode and a second counter electrode, for electrically coupling a first piezoelectric element unit and a second piezoelectric element unit, for composing a thin film piezoelectric element are common floating electrodes. A first principal electrode film and a second principal electrode film of each piezoelectric element unit are connected, and a voltage is applied between the two piezoelectric element units. As a result, by the wiring of two terminals only without using grounding electrode wiring, the first piezoelectric element unit and second piezoelectric element unit can be driven, so that the wiring process may be substantially simplified.