20 b includes a diaphragm 21 b a piezoelectric film 22 b a spacer 23 b and fixed portions 24 b as in the foregoing embodiments the diaphragm 21 b and the piezoelectric film 22 b are connected at opposed fixed end areas 24 b the unstressed shape of the diaphragm 21 b and the prestressed state of the piezoelectric film 22 b are chosen to ensure that the diaphragm 21 b lies in a flat plane before any excitation voltage is applied to the piezoelectric film 22 b more specifically an initial shape of the diaphragm 21 b in a state where the diaphragm 21 b is not connected with the piezoelectric film 22 b is a downwardly protruding shape the tensile force of the piezoelectric film 22 b is set such that the diaphragm 21 b is deformed into a flat shape by the tensile force applied by the piezoelectric film 22 b and an external force applied by the spacer 23 b the fixed portions 24 b are provided respectively near the opposite ends of the diaphragm 21 b and the piezoelectric film 22 b which are connected with each other the fixed portions 24 b protrude downward in the thickness direction of the vibrating device 20 b the fixed portions 24 b are preferably supported on an installation surface of a table or the like and prevent the diaphragm 21 b and.