Patent ID: 8212626

Claim:
A constant-temperature type crystal oscillator comprising: a surface-mount crystal unit, in which a crystal element is housed in a case main body to hermetically encapsulate the crystal element with a metal cover, and which comprises a crystal terminal serving as a mounting terminal that is electrically connected to at least the crystal element on an outer bottom face of the case main body; a thermistor that detects an operational temperature of the surface-mount crystal unit; and a circuit substrate, on which elements forming an oscillator circuit along with the surface-mount crystal unit and elements forming a temperature control circuit along with the thermistor are installed, wherein the thermistor comprises: a first terminal electrode; a second terminal electrode; and a temperature detecting electrode that is electrically independent of the first terminal electrode and the second terminal electrode, and wherein the temperature detecting electrode is electrically connected to the crystal terminal of the surface-mount crystal unit through a circuit pattern formed on the circuit substrate.