An optical transmission device includes: a reception unit configured to receive a plurality of light beams and wavelength allocation information of optical signals included in each of the light beams; a demultiplexing unit configured to demultiplex the plurality of light beams received; a plurality of switches configured to switch between transmitting or blocking with respect to the demultiplexed plurality of light beams; a multiplexing unit configured to multiplex light beams transmitted from the plurality of switches; a monitoring unit configured to monitor an intensity of the multiplexed light beams; and a controller configured to, based on the wavelength allocation information, obtain a combination of the light beams not including the optical signals having overlapping wavelengths, and control the plurality of switches in accordance with the combination.