To provide a piezoelectric oscillator in which, even after a first package and a second package are bonded to each other, the connection state can be easily observed externally, so that testability can be enhanced, and connection failure can be easily found out to perform a repair. A piezoelectric oscillator includes a first package housing a piezoelectric resonator element therein and having external terminal portions connected to excitation electrodes of the piezoelectric resonator element, and a second package housing an oscillating circuit element, the first package being superposed on and fixed to the second package. Herein, in the second package, the oscillating circuit element, which is connected to a lead frame, is molded out of resin, and connection terminal portions and mounting terminals formed of the lead frame are exposed at the second package. Furthermore, the external terminal portions of the first package are exposed at the side surfaces of the first package, and the external terminal portions and the connection terminal portions of the second package are electrically connected to each other by a conductive material.
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