A connection device for selecting an optimum receiver includes a single first port, in which a transmitter is connected via a bidirectional type cable, and a plurality of second ports, in which a plurality of receivers are connected via respective bidirectional type cables. The connection device further includes a transmission control unit which acquires transmitter function information from the transmitter via the first port as well as acquiring receiver function information from each of the plurality of receivers via their respective second ports. A transmission control unit links together the first port and the respective second port from among the plurality of second ports, which is connected to the receiver which is endowed with receiver function information closest to the transmitter function information.