A ceramic substrate 1 comprises a thin diaphragm portion 3 and a thick portion 2. A lower electrode 4 is formed on the ceramic substrate and is spaced apart from an auxiliary electrode 8, also formed on the ceramic substrate. A bonding layer 7C comprises an insulator and is formed on the ceramic substrate between the lower and auxiliary electrodes. A piezoelectric/electrostrictive layer 5 is formed on at least a portion of each of the lower electrode, the auxiliary electrode and the bonding layer. An upper electrode 6 extends over the piezoelectric/electrostrictive layer and contacts the auxiliary electrode. A bonded portion exists wherein the bonding layer serves to completely bond together the substrate and the piezoelectric/electrostrictive film layer.