PURPOSE: To miniaturize an oscillator and also to widen the frequency dead band by providing an inductor forming electrode connected to an interdigital electrode in addition to the side electrode for exciting a surface acoustic wave on a piezoelectric substrate so as to eliminate the need for an inductor as a discrete component and decrease the capacitance ratio.

CONSTITUTION: The interdigital electrode 12 for exciting surface acoustic wave made of aluminum thin film having a thickness of, e.g., 0.1μm is provided on the piezoelectric substrate 11 to propagate a surface acoustic wave and grating reflectors 13, 14 where 200 strip conductors each having a length of 1/4 of the surface acoustic wavelength and a width of nearly 1.0μm are arranged respectively at both sides ae provided so as to constitute a one-terminal pair surface acoustic wave resonator. Moreover, the inductor forming electrode 15 comprising a spiral strip conductor is connected to one end of the interdigital electrode 12. The electrode 15 is formed on the piezoelectric substrate 11 constituting the surface acoustic wave resonator and connected in serieswith the resonator.