PURPOSE: To reduce the deviation in FM modulation sensitivity between channels by providing a bias control circuit for a modulating variable capacity diode of a voltage control oscillator and controlling said bias control circuit with a channel designating signal.

CONSTITUTION: A channel designating signal supplied from an input terminal 9 for channel designating signal is applied to a programmable counter 8 to set the number of divisions and also supplied to a bias control circuit 10. The output voltage, of the circuit 10, i.e., the bias voltage VMOD is set at V2 higher than V0 to function to lower the modulation sensitivity in case a channel is changed to a center frequency fa of LCH. While said bias voltage is set at V1 lower than V0 to increase the modulation sensitivity when the channel is changed to a center frequency fc of HCH. In such a way, the variation of the modulation sensitivity is reduced. This reduces the deviation in modulation sensitivity between channels.