Provided is an optical network which makes it possible to increase frequency use efficiency of an optical signal when transmitting wavelength division multiplexed light. One or more optical path cross connection devices (OXC) through which a wavelength division multiplexed light signal travels when being transmitted from a prescribed transmission node to a prescribed receiving node, wherein when an optical channel inputted from an input optical fiber (Fi1-Fin) is routed or switched to one or more output optical fibers (Fo1-FoN), a plurality of optical channels adjacent on a frequency axis which are outputted to the same output optical fiber (FoN) in the input optical fibers (Fi1-Fin) are routed or switched to an output optical fiber by demultiplexing the plurality of optical channels as one bundle without demultiplexing each of the optical channels individually. Thus, it is possible to increase frequency use efficiency of an optical signal when transmitting wavelength division multiplexed light, because the instances of optical channel filtering are reduced and the loss caused by filtering is decreased.