A piezoelectric actuator includes piezoelectric material layers, individual electrodes corresponding to pressure chambers, a first common constant electric potential electrode corresponding to outer peripheral portions of the pressure chambers, and a second common constant electric potential electrode corresponding to central portions of the individual electrodes. A plurality of first active portions is formed in areas of the piezoelectric material layers sandwiched between the individual electrodes and the second common constant electric potential electrode, and a plurality of second active portions is formed in areas of the piezoelectric material layers sandwiched between the individual electrodes and the first common constant electric potential electrode. Since the second common constant electric potential electrode has a mesh-shaped form, it is possible to reduce an impedance thereof.