A light signal multiplexer and a light signal demultiplexer corresponding to the light signal multiplexer. The light signal multiplexer may include a reflector and a filter, in which the reflector is disposed on a plurality of input light paths to allow a plurality of light signals input along the input light paths to be reflected toward the filter disposed on at least one output light path, and the filter is disposed to allow the light signals reflected toward the filter to be reflected along the at least one output light path, and thus the light signal multiplexer may individually set the input light paths for the light signals.