Disclosed herein is a demodulator, including: a frequency synchronization section adapted to synchronize a frequency of a local oscillation signal to be produced on the demodulator side with a local oscillation frequency of a modulation signal transmitting from a modulator side; a demodulation signal production section adapted to produce a demodulation signal based on the local oscillation signal synchronized by the frequency synchronization section and the modulation signal transmitted from the modulator; and a direct current correction section adapted to detect a direct current voltage of the demodulation signal from the demodulation signal produced by the demodulation signal production section and correct the direct current voltage of the demodulation signal so that the direct current voltage becomes equal to a reference voltage set in advance.