PURPOSE: To reduce the number of components by providing a switch element composed of a wavelength selection filter, a time switch and a wavelength conversion element and disposing the elements on respective cross points of input/output highway matrices to connect them.

CONSTITUTION: An optional wavelength of a signal light sent through input highways #1IN-#mIN subjected to time division multiplex and wavelength division is selected at a filter F in a switching element SE at the prescribed cross point of a matrix M and converted into a signal on a desired time base at a time switch TS, converted into a desired wavelength at a wavelength conversion element W and outputted to respective output highways #1OUT-#mOUT. Thus, the signal light is sent from the input highway to the output highway while being subjected to a prescribed conversion in one stage of conversion. Through the constitution above, the number of memories, selection filters and wavelength conversion elements are minimized to constitute high performance speech path.