PURPOSE: To compensate the change of an oscillation frequency caused by the change of the capacitance of a variable capacity diode due to a temperature change and the change of the resonance frequency of a surface acoustic wave resonator due to the temperature change.

CONSTITUTION: A voltage control type oscillator 10 is provided with a variable capacity diode 16 generating capacitance by reverse direction voltage applied on a cathode terminal and forming a capacitor, a surface acoustic wave resonator 12 resonating by a prescribed resonance frequency and a feedback circuit composed of capacitors 26, 28 and 30 performing the feedback of a signal of an amplified resonance frequency to the surface acoustic wave resonator 12. By the capacitors 26 and 28 of the feedback circuit where capacitance changes by a negative inclination due to the inclination of a temperature change, the change of an oscillation frequency caused by the change of the capacitance of a variable capacity diode 16 due to the temperature change and the change of the resonance frequency of the surface acoustic wave resonator 12 due to the temperature change are compensated.