In a voltage-controlled oscillator capable of broadening a variable frequency range while suppressing increase of conversion gain, a converter (12) converts an input voltage to a first physical quantity, a variable converter (13) supplies a second physical quantity that accords with the status of each switch of a switch group (13a). another variable converter (14), when the input voltage is contained within a prescribed voltage range, supplies a third physical quantity that accords with the input voltage and the status of each switch of another switch group (14a), and a variable-frequency oscillator (15) supplies a signal of a frequency that accords with the first physical quantity, the second physical quantity, and the third physical quantity.