PURPOSE: To provide a large displacement of amplitude without changing the thickness of a piezoelectric bimorph device as well as reducing its mechanical strength by forming a through-hole of smaller area than a metal substrate, both sides of which piezoelectric substrates are stuck to, and filling the through hole with a filler.

CONSTITUTION: A rectangular through hole is formed on an iron-made metal substrate 11. A vinyl chloride resin filler 14 of the same shape as the through hole is set inside the through hole and embedded there by bonding with a polymer bonding agent. The thickness of the filler 14 is set to be the same as the metal sheet 11. A piezoelectric bimorph device comprises two piezoelectric substrates 12 and 13 stuck to both sides of the metal substrate. The piezoelectric substrates 12 and 13 have electrodes 12a, 12b, 13a, and 13b formed on both main surfaces, and are bonded to the metal substrate 11 so that the direction of polarization is in the same direction. Also, a lead terminal 15 is connected to the metal substrate 11, and lead terminals 16 and 17 are connected to the electrodes 12a and 13a which are not in contact with the metal substrate.