To provide a structure of a small piezoelectric oscillator which can accept the dimension of the size of the external form of a piezoelectric oscillator container and has a high production yield with an integrated circuit element mounted to a lid of the piezoelectric oscillator container to bring about high productivity.

The piezoelectric oscillator is provided with a piezoelectric oscillation element mounted to a bottom surface in a recessed space in a recessed container, external connecting terminals formed at four corners of the outside bottom surface of the recessed container, and an integrated circuit element connected electrically to the piezoelectric oscillation element embedded with an oscillation circuit. In the structure of the piezoelectric oscillator, an almost rectangular flat plate-shaped lid of an insulating member is mounted, hermetically sealed, on a surface in which an electric connection path is formed at the upper edge of an opening of the recessed container in a form of blocking the recessed space, the integrated circuit element is mounted to the surface of the lid through a lid composed of the recessed space and ceramic on an opposite side.