To provide a temperature controlled crystal oscillator with which heating power is reduced and a prescribed oscillation frequency can be provided in a short time by forming a heating pattern on a crystal board as a heat generating part, impressing external power supply and directly heating the crystal board.

A crystal board 1 to oscillate the prescribed frequency, an electrode pattern 2 for transmitting the original oscillation of the crystal board 1 and an electrode 3 for transmitting an oscillate signal to the outside while being connected to the electrode pattern 2 are provided. Besides, this oscillator is composed of an insulator 4 for holding the electrode 3, cap 5 and heat generating pattern 6 for heating the crystal board 1. The heat generating pattern 6 generates heat by impressing power from the newly provided electrode 3. Since the heat generating part is provided on the crystal board 1, when heating the crystal board 1, a heater fitted to the cap 5 as a heat generator is not required. Since conventionally required time for balancing the heat exchange of each component of a heat path is unnecessitated and a heating area is reduced, power required for heating can be reduced.