To provide a voltage-controlled oscillator capable of obtaining an increased variable range of oscillation frequencies.

When a control voltage Vtune is the same, the oscillation frequency with only switches SW3, SW4 turned on is higher than that with only switches SW1, SW2 turned on. Accordingly, even if the oscillation frequency with only the switches SW1, SW2 turned on is lower than a designed value and a desired oscillation frequency cannot be obtained by controlling the capacitance of varactors D1, D2, the desired oscillation frequency can be obtained, by tuning only the switches SW3, SW4 to control the capacitance of the varactors D1, D2. That means, for the oscillation frequency, coarse tuning can be performed by controlling the switches SW1-SW4, and fine tuning can be performed by the varactors D1, D2. As this result, the range of the oscillation frequency is increased.