Light signal transmitter units 21-1 to 21-n of a transmitter device 20 perform optical communication with a receiver device 40 via optical fiber cables 61-1 to 61-n of an optical interface cable 61. A connection detection unit 22 detects whether connection to the receiver device is established via the optical interface cable, and a visible light source control unit 24 causes a visible light source unit 25 to emit visible light that can identify by an attribute a connection relationship with the receiver device connected via the optical interface cable, only when the connection to the receiver device 40 is not detected, and causes visible light superposition units 26-1 to 26-n to superpose the visible light on the cable. The receiver device also superposes on the cable the visible light that can identify by the attribute the connection relationship with the transmitter device connected via the optical interface cable, only when the connection to the transmitter device 20 is not established, in the same way as the transmitter device. The connection between the optical communication devices can be correctly and easily performed by using the optical transmission path.