A cable apparatus makes a selection between supply of an internal power to a predetermined interface device and that of an external power to the interface device in compliance with the interface standard applied to the predetermined interface device. The cable apparatus includes an internal power terminal connectable to an internal power source, a plurality of external power terminals connectable to an external power source, and a plurality of power lines connected to the internal power terminal and/or external power terminals. A power line selection controller is included to select, when an internal power is supplied from the internal power terminal, one of the power lines that allows a connection of the internal power from the internal power terminal to the plurality of external power terminals and when an external power is supplied from any one of the external power terminals, one of the power lines that allows to connect the external power from the external power terminal to the other external power terminals.