To provide a piezoelectric oscillator which can be reduced in size by reducing the planar size. With regard to a layered lead frame comprising two lead frames and, connection leads for connection with a piezoelectric resonator are formed on the upper lead frame and the connection leads are erected upwards so as to form connection terminals, and mounting leads for mounting to a mounting board are formed on the lower lead frame and the mounting leads are erected downwards so as to form mounting terminals, and an IC forming an oscillating circuit is mounted on the layered lead frame, the piezoelectric resonator formed by sealing a piezoelectric resonator element within a package is mounted on the layered lead frame, and the layered lead frame and the piezoelectric resonator are sealed within a resin package such that the principal surface of the mounting terminals are exposed outwards, thereby forming a completed article.