A ink jet print head includes an actuator substrate having an ink flow path including a pressure chamber, a movable membrane forming layer including a movable membrane disposed on the pressure chamber and defining a ceiling surface portion of the pressure chamber, a piezoelectric element formed on the movable membrane and including a lower electrode, a piezoelectric film formed on the lower electrode and an upper electrode formed on the piezoelectric film, with the pressure chamber, the movable membrane and the upper electrode having a rectangular shape elongated in one direction in plan view as viewed from a direction normal to the movable membrane, the lower electrode including a main electrode section constituting the piezoelectric element and an extension section extending from the main electrode section along a surface of the movable membrane forming layer, and a dimension measuring pattern related to the pressure chamber.