A frequency converter includes a voltage-current converter circuit which generates a positive-phase input current signal and a negative-phase input current signal, a switching circuit which switches between the positive-phase input current signal and the negative-phase input current signal according to a positive-phase local oscillator signal and a negative-phase local oscillator signal to generate a positive-phase output current signal and a negative-phase output current signal, an amplifier circuit which current-voltage converts and amplifies the positive-phase output current signal and negative-phase output current signal to generate a positive-phase output voltage signal and a negative-phase output voltage signal, and a plurality of CR circuits which are inserted at least either between the voltage-current converter circuit and the switching circuit or between the switching circuit and the amplifier circuit and each of which includes at least one capacitor through which high-frequency components pass and at least one resistance through which low-frequency noise components pass.