Abstract: A radar oscillator has an oscillation unit and first and second switch circuits. The first switch circuit turns off an electric power supply to an amplifier in a non-input period of a pulse signal to set the oscillation unit in a non-oscillation state and turns on the electric power supply to the amplifier in an input period of the pulse signal to set the oscillation unit in an oscillation state. The second switch circuit turns on an electric power supply to an LC resonator in a period immediately before the pulse signal is input in a period in which the pulse signal is not input to supply a current to the LC resonator and turns off the electric power supply to the LC resonator at a timing at which the pulse signal is input, so that activation of an oscillation operation of the oscillation unit is accelerated.