Optical switch module and optical relay apparatus and path expansion method that use optical switch module

An optical switch module includes: N first input ports to which a signal is input; M first output ports from which a signal is output; an M×N switch to include N second input ports and M second output ports, and to set a path between the second input ports and the second output ports, the second output ports coupling with the first output ports, respectively; a test-signal input port to which a test-signal is capable of being externally input; an expansion port from which one of the test-signal and the signal from any one of the first input ports is output; and an optical switch to selectively connect at least one of the test-signal and the signal from any one of the first input ports to at least one of the expansion port and any one of the second input ports, wherein both N and M are natural numbers.