[Problem] To provide an optical transmission device that, while suppressing band narrowing due to optical filters, achieves flexibility of optical communication such as wavelength reutilization and that supports a flexible grid.[Solution] An optical transmission device according to the present invention is provided with a cyclic AWG that filters respective optical signals inputted to each input port. The respective optical signals are constituted so that a plurality of wavelength-multiplexed signals can be allocated within one channel band, the respective optical signals are filtered in channel units, and the pass-band width of each of the input ports of the cyclic AWG corresponds to the bandwidth of a channel.