In a method for manufacturing a piezoelectric device, a silicon oxide film is deposited by sputtering on a surface of a single-crystal piezoelectric substrate closer to an ion-implanted region, and a silicon nitride film is deposited by sputtering on a surface of the dielectric film opposite to a side thereof closer to the single-crystal piezoelectric substrate. The silicon oxide film has a composition that is deficient in oxygen relative to the stoichiometric composition. Accordingly, little oxygen is supplied from the silicon oxide film to the piezoelectric thin film during heat treatment of a piezoelectric device. This prevents oxidation of the piezoelectric thin film and therefore formation of an oxide layer with high resistivity in the piezoelectric thin film. As a result, a pyroelectric charge generated in the piezoelectric thin film can flow to the silicon oxide film.