According to one embodiment, a cable includes a first plug and a second plug, a voltage application line which is formed by a metal wire connected between the first plug and the second plug, and to which a voltage is applied from one of the first plug and the second plug, a plurality of optical fibers which are connected between the first plug and the second plug, and transmit a video signal, and a controller connected to the voltage application line, and configured to detect a transmission direction of the video signal between the first plug and the second plug by sensing a change in voltage of the voltage application line and perform processing in accordance with the detected transmission direction.