A piezoelectric composite thin-film resonator has good temperature stability and resonance response, in a fundamental thickness-extensional vibration mode. Spurious vibrations caused by even-number order harmonic overtones are suppressed. The resonator has a thin film of SiO.sub.2 or other materials having a resonant frequency temperature coefficient which is opposite to that of the piezoelectric material. The SiO.sub.2 layer is inserted between two thin films of ZnO, CdS, AlN, or other piezoelectric materials. This sandwiched structure is positioned between a pair of electrode films and is supported by an insulative or a semiconductive film which is in turn fixed to a substrate. The thicknesses of the thin films have values such that an overall temperature coefficient of the resonant frequency may be at or near substantially zero. In order to better remove the even-number order harmonics, it is preferable to cover the upper electrode film with a thin film of semiconductor or insulator material.