Optical signal processing device that processes an optical signal based on predetermined data has a first terminal for inputting and outputting the optical signal, which is connected to a first channel of optical communication line, a second terminal for inputting and outputting the optical signal, which is connected to a second channel of optical communication line, and a switch portion for optical communication, which is connected to the first and second terminals. The switch portion chooses any one of the first and second channels of the optical communication lines without depending on any external fiber channel hub and any fiber channel switch.