A voltage control oscillator which has an oscillator circuit comprising at least an inductive resonator, active element, and variable capacitance diode and externally applies a direct current control voltage to the variable capacitance diode through a bias circuit to change an oscillation frequency by altering a capacitance value of the variable capacitance diode with variations of the direct current voltage, comprising bias circuit is a low-pass filter comprising a resistor and a capacitor and the oscillation frequency is set higher than a cut-off frequency of the low-pass filter.