An oscillation circuit includes a circuit for frequency adjustment, a variable capacity control circuit in which a voltage to be output therefrom is controlled with either a voltage which is input from a terminal T1 or a voltage other than the voltage which is input from the terminal T1, a circuit for oscillation which is provided with a varactor and to which a signal from the circuit for frequency adjustment and a signal from the variable capacity control circuit are input, and a three-terminal switch which outputs the voltage which is input from the terminal T1 to either the circuit for frequency adjustment or the variable capacity control circuit.