PURPOSE: To provide satisfactory characteristics by eliminating the distribution loss of optical signals with simple configuration by arranging wavelength multiplexing/demultiplexing means over a lot of stages, connecting the respective stages in a prescribed wiring pattern and providing the wavelength multiplexing/ demultiplexing means for each stage.

CONSTITUTION: The optical signals of wavelengths λ1, λ2, λ3... are inputted from input ports 61 and 62, the optical signals of wavelengths λ1, λ3, λ5... are outputted to an output port 71, and the optical signals of wavelengths λ2, λ4, λ6... are outputted to an output port 72. Cycle filters 31-34 at the first stage multiplex/demultiplex the wavelengths λ1-λ4 of the first group to the port 71 and the wavelengths λ5-λ8 of the second group to the port 72. The cycle filters 31-34 at the first step distribute the correspondent wavelengths to respective output ports 21-28. Filters 41-43 corresponding to the group of wavelength λ1-λ4 multiplex/demultiplex the wavelength λ1 and λ2 of the first group to the output port 71 and the wavelengths λ3 and λ4 of the second group to the output port 72. Filters 42 and 44 corresponding to the group of wavelengths λ5-λ6 multiplex/ demultiplex the wavelengths λ5 and λ6 to the port 71 and the wavelengths λ7 and λ8 to the port 72. Filters 51-54 are similarly operated as well.