PURPOSE: To obtain an oscillation frequency signal subject to temperature compensation over a wide temperature range by providing at least a reactance compensation circuit compensating a low temperature region of a crystal oscillator and a control voltage generating circuit compensating a high temperature region of the crystal oscillator.

CONSTITUTION: The reactance compensation circuit 1 keeps the frequency to a constant value by compensating the reactive component of a Colpitz oscillation circuit 3 through the change in a series resistor of a thermister TH1 caused attended with temperature change at a low temperature region. Further, the control voltage generating circuit 2 keeps the frequency constant by applying a control voltage generated at a emitter of a transistor TR2 due to the change in the series resistor of a thermister TH2 generated attended with temperature change at a high temperature region to a varactor diode VD1 so as to compensate the capacitance of the Colpitz oscillation circuit 3. Further, capacitors C3, C5 apply temperature compensation at a medium temperature region. Then the oscillation frequency signal with less frequency fluctuation to a range between -30°C∼+70°C very wider than a conventional circuit is obtained as shown in figure (d).