PURPOSE: To make the size of an oscillator small and to reduce the cost by allowing a DC-DC converter to convert its received DC voltage into a DC voltage in response to the ambient temperature and providing an output of the voltage to a piezoelectric element adhered to a rear side of a surface acoustic wave element.

CONSTITUTION: When a low voltage is applied to a temperature compensation oscillator 10 from a low voltage power supply 15, an oscillating circuit 16 is oscillated at a resonance frequency of a surface acoustic wave element 12. On the other hand, a DC-DC converter 11 detects its ambient temperature with a thermister and boosts the voltage received from the low voltage power supply 15 into a voltage in response to the temperature and provides the voltage to a piezoelectric element 13. Since the piezoelectric element 13 is extended or contracted depending on the voltage outputted from the converter 11, an interval of comb teeth of interdigital electrodes of the element 12 adhered to the element 13 is changed to change the oscillating frequency of the oscillating circuit 16. The temperature compensation oscillator 10 oscillating a prescribed oscillating frequency at all times is obtained even when the ambient temperature changes by controlling the oscillating frequency of the circuit 16 with a voltage in response to the temperature outputted from the converter 11 in this way.