A substrate is formed with a chamber having an opening which is defined by first edges extending in a first direction with a first dimension and second edges extending in a second direction perpendicular to the first direction with a second dimension shorter than the first dimension. A vibration plate is provided on the substrate so as to seal the opening. A first common electrode to be fixed at a predetermined potential is formed on the vibration plate. A first piezoelectric layer is laminated on the first common electrode so as to oppose the chamber. The first piezoelectric layer extends in the first direction such that both end portions thereof in the first direction are beyond the second edges of the opening. A drive electrode to which a drive signal is supplied externally is laminated on the first piezoelectric layer. A second piezoelectric layer is laminated on the drive electrode so as to oppose the chamber. The second piezoelectric layer extends in the first direction such that both end portions thereof in the first direction are beyond the second edges of the opening. A second common electrode to be fixed at the predetermined potential is laminated on the second piezoelectric layer.