A piezooscillator having a piezoelectric vibrator and an oscillation circuit in a space surrounded by a substrate and a cover, which has a smaller size and height, and further, which can be assembled easily and suppress power consumption, is provided. The piezooscillator includes a recessed portion formed on the surface of the substrate; a supporting member supporting the piezoelectric vibrator while the piezoelectric vibrator is in a state partially or entirely accommodated in the recessed portion and floating from the substrate; a heating element provided on the surface of the piezoelectric vibrator; a temperature sensitive element provided in the space; and a temperature control unit provided in the space and controlling power supply to said heating element based on an output of the temperature sensitive element, in which, it is possible to reduce capacity of the space accommodating the piezoelectric vibrator and the heating element by eliminating the need of an additional substrate provided above the substrate as in conventional piezoelectric vibrators, so that the size and height of the piezooscillator can be reduced, in which assembling is eased, and power consumption can be reduced on the back of suppressed heat release to the substrate.