A piezoelectric speaker improved in acoustic features by weight reduction of a diaphragm of the piezoelectric speaker without decreasing stiffness of the diaphragm or a coefficient of thermal expansion of surfaces of the piezoelectric speaker is provided. The diaphragm having placed thereon a piezoelectric element is made of a sandwich-laminate clad material using different materials. For example, surface materials made of 42 alloy each having a thickness of 10 m and a core material made of aluminium having a thickness of 30 m form a clad material having a thickness of 50 m. The formed clad material is processed into an arbitrary shape to form the diaphragm of the piezoelectric speaker. With this diaphragm, it is possible to keep the stiffness and the coefficient of thermal expansion of the 42-alloy diaphragm having the thickness of 50 m, and also achieve weight reduction by approximately 40%.