The invention has: a first register that is set when receiving a CEC message which a video signal source reads an EDID of a video transmitting apparatus and issues and is reset in response to a leading edge of 5V that is supplied from the video signal source; and a second register which reads an EDID of a video displaying apparatus, is set when it is decided that the video displaying apparatus is a predetermined video displaying apparatus, and is reset when a state where an HPD is in a state of “L” has continued for a predetermined period of time or longer. Only when both of the first and second registers have been set, it is determined that a predetermined video signal source, the video transmitting apparatus, and the video displaying apparatus have directly been connected.