To obtain a voltage-controlled oscillation circuit with widened allowable varying range of the threshold voltage for a depression-type electric field effect transistor, which can be oscillated by a desired frequency in the voltage controlled oscillating circuit connected with odd-number of inverters in a ring form so as to respectively vary the delaying time of the inverters according to controlled voltage.

This circuit is provided with a 2:1 selector 2 provided within a ring to receive the output signal of a (2n-1)-numbered (n: positive number) inverter at one input terminal, to receive the output signal of a (2n+1)-numbered inverter at the other input terminal and to output one of the signals and is provided with a selector control circuit 3 outputting a switching signal for allowing the 2:1 selector to select the signal inputted to one input terminal at the time of deviating in the direction of making the threshold voltage of D-FET which is a load on the output signal of the inverter smaller than a designed value and to select the signal inputted to the other input terminal when it deviates to the increasing direction.