[Problem] To provide an optical transmission/reception device, an optical communication system, an optical communication method, and a program which are capable of securing the confidentiality of information included in an optical signal even when the optical signal is transferred to a device that is not an original transmission destination device.[Solution] This optical transmission/reception device is provided with: a wave separation unit for receiving a wavelength-multiplexed optical signal and separating the same into a plurality of optical signals; a plurality of reception units for receiving each of the plurality of optical signals separated by the wave separation unit; a plurality of output units for outputting optical signals differing in wavelength from each other; a control unit for requesting, in response to the inclusion in the received wavelength-multiplexed optical signal of an optical signal to which a prescribed process has been applied, that a prescribed change be applied to the optical signal outputted by at least one of the plurality of output units; and a wave combining unit for combining the plurality of optical signals outputted from the plurality of output units and outputting the combined signal.