To provide a light frequency conversion device which takes out optical signal components having a desired wavelength from frequency multiplexed signals that are transmitted by optical intensity modulation without using a variable type optical filter.

A locally generated signal source 110 outputs locally generated signals. A locally generated light source 120 outputs locally generated light signals that are optically intensity modulated in accordance with the locally generated signals. A multiplexing section 130 multiplexes the locally generated light signals and inputted frequency multiplexed signals. An optical frequency converting section 140 opto-frequency converts optical signals outputted from the section 130 by quadri-light wave mixing using a nonlinear effect and frequency-converts the frequency multiplexed signals the are modulation signals. An optical filter section 150 extracts only optical signal components having a desired light frequency from the optical signals outputted from the section 140. An opto-electric conversion section 160 converts the optical signals extracted by the section 150 into electric signals and outputs the signals. A band pass filter section 170 extracts only electric signals having a desired modulation frequency from the electric signals outputted from the section 160.