PURPOSE: To obtain the frequency control circuit configured simply at a low cost in which a stable frequency signal is obtained even in the case of momentary interruption of the circuit power supply.

CONSTITUTION: When a momentary interruption detection section 5 detects momentary interruption of the circuit power supply, a frequency control backup voltage generating section 6 generates a prescribed frequency control voltage based on a backup power supply 7 provided independently of the circuit power supply. The prescribed frequency control voltage is applied to a voltage controlled oscillator 4.