Abstract: An optical routing system where a time-division multiplexing signal train passes through a front stage semiconductor laser amplifier and detects information of a header and is multiplexed with a local oscillator light from a variable wavelength light source and passes through a rear stage semiconductor laser amplifier, and then is demultiplexed by an optical wavelength division demultiplexer and is outputted to an output side optical signal transmission fiber and an intermediate output port. Wavelength of the local oscillator light and selective wavelength of the optical wavelength division demultiplexer are selected so that a packet is outputted to an assigned intermediate output port. Thereby for the time-division multiplexing optical signal train, while the optical signal train as a whole is held, a specified part or a packet can be distributed.