A piezoelectric actuator includes a vibrating plate including a first surface that closes an opening provided in a substrate and a second surface in which a plurality of piezoelectric elements is provided, a suppression part configured to suppress a vibration of the vibrating plate, and a first wall and a second wall protruding from the first surface to the opening. When a portion where the first electrode, the piezoelectric layer and the second electrode overlap each other is an active part of the piezoelectric element, the first wall and the second wall are provided to sandwich the active part in plan view from the stacking direction of the first electrode, the piezoelectric layer and the second electrode, and the second wall is different from the first wall at least in one of the width, height, length and physical property.