An inkjet head comprising: a displacement film that includes a driving film operable to expand and contract in a direction perpendicular to a thickness direction of the driving film, the displacement film being operable to undergo curving deformation in a thickness direction of the displacement film caused by the expansion and contraction of the driving film, wherein the driving film is a piezoelectric thin film, the inkjet head further comprises upper and lower electrodes (15, 13) for applying a voltage across the piezoelectric thin film, the upper and lower electrodes (15, 13) being disposed so as to sandwich the piezoelectric thin film in a thickness direction of the piezoelectric thin film, a substrate that includes a hole portion formed therein in a thickness direction thereof and that supports the displacement film such that the displacement film covers the hole portion so as to allow expansion and contraction of the driving film to cause the curving deformation of the displacement film in the thickness direction of the displacement film in an area of the displacement film corresponding to the hole portion; and an ink discharge portion that includes an ink chamber holding ink and that discharges the ink to outside the ink discharge portion by having pressure resulting from the curving deformation of the displacement film applied to the ink, wherein the ink discharge portion is disposed on a side opposite to the hole portion of the substrate with respect to the displacement film, wherein the ink discharge portion comprises a nozzle substrate including a nozzle hole through which to discharge the ink, wherein the ink discharge portion comprises a partition portion disposed on the upper electrode and closer to the displacement film than the nozzle substrate is and constitutes a side wall of the ink chamber with the upper electrode, characterized in that: the piezoelectric thin film is formed over the hole portion of the substrate, and over the side wall of the hole portion of the substrate, in that: the partition portion is formed on the upper electrode to have an opening width, which is an inner diameter of the ink chamber, and which is wider than an opening width of the hole portion in the substrate, and in that: the displacement film is operable to be displaced when a voltage is applied across the piezoelectric thin film in its thickness direction by the lower electrode and the upper electrode. a displacement film that includes a driving film operable to expand and contract in a direction perpendicular to a thickness direction of the driving film, the displacement film being operable to undergo curving deformation in a thickness direction of the displacement film caused by the expansion and contraction of the driving film, wherein the driving film is a piezoelectric thin film, the inkjet head further comprises upper and lower electrodes (15, 13) for applying a voltage across the piezoelectric thin film, the upper and lower electrodes (15, 13) being disposed so as to sandwich the piezoelectric thin film in a thickness direction of the piezoelectric thin film, a substrate that includes a hole portion formed therein in a thickness direction thereof and that supports the displacement film such that the displacement film covers the hole portion so as to allow expansion and contraction of the driving film to cause the curving deformation of the displacement film in the thickness direction of the displacement film in an area of the displacement film corresponding to the hole portion; and an ink discharge portion that includes an ink chamber holding ink and that discharges the ink to outside the ink discharge portion by having pressure resulting from the curving deformation of the displacement film applied to the ink, wherein the ink discharge portion is disposed on a side opposite to the hole portion of the substrate with respect to the displacement film, wherein the ink discharge portion comprises a nozzle substrate including a nozzle hole through which to discharge the ink, wherein the ink discharge portion comprises a partition portion disposed on the upper electrode and closer to the displacement film than the nozzle substrate is and constitutes a side wall of the ink chamber with the upper electrode, characterized in that: the piezoelectric thin film is formed over the hole portion of the substrate, and over the side wall of the hole portion of the substrate, in that: the partition portion is formed on the upper electrode to have an opening width, which is an inner diameter of the ink chamber, and which is wider than an opening width of the hole portion in the substrate, and in that: the displacement film is operable to be displaced when a voltage is applied across the piezoelectric thin film in its thickness direction by the lower electrode and the upper electrode.