<p>It is possible to realize a highly effective optical OFDM receiver. Provided is a subcarrier separation circuit which receives an optical OFDM signal formed by two subcarriers A and B and separates subcarrier components. A reception signal light and a local oscillation light are inputted and converted into a baseband electric signal. The baseband electric signal is converted into a digital signal. The converted digital signal is frequency-shifted so that the center frequency of the subcarrier A is zero. The frequency-shifted signal is added to the signal obtained by delaying the frequency-shifted signal by a 1/2 symbol time, thereby separating the component of the subcarrier A.</p>
