An AV signal output device, comprising: first communications signal lines and first differential signal lines for transmitting differential signals that are metal wires; first optical signal lines for transmitting optical output signals; a first connector for connecting said signal lines (160, 170, 180) to a destination through a cable, said first connector having a first optical transmission path for transmitting optical output signals; a selection output controller which receives an AV signal as input, selects differential signals or optical output signals, and outputs the AV signal to the first connector using the selected signals; and an information identification unit configured to read out information of a connected destination of the first connector through the first communications signal lines, wherein the information identification unit includes an optical information identification unit which - identifies optical information from the information read out from the connected destination including information on optical capability indicating whether optical signals can be received by the connected destination of the first connector and optical connection information indicating successful reception of optical signals by the connected destination of the first connector, and - outputs optical information identified using both the information on optical capability and the optical connection information to the selection output controller; when the selection output controller determines to make an optical connection based on the optical information, the selection output controller outputs the AV signal using the optical output signals, and when the selection output controller determines to not make an optical connection based on the optical information, the selection output controller outputs the AV signal using the differential signals, and the AV signal output device is configured to supply and receive power through the first communications signal lines. first communications signal lines and first differential signal lines for transmitting differential signals that are metal wires; first optical signal lines for transmitting optical output signals; a first connector for connecting said signal lines (160, 170, 180) to a destination through a cable, said first connector having a first optical transmission path for transmitting optical output signals; a selection output controller which receives an AV signal as input, selects differential signals or optical output signals, and outputs the AV signal to the first connector using the selected signals; and an information identification unit configured to read out information of a connected destination of the first connector through the first communications signal lines, wherein the information identification unit includes an optical information identification unit which - identifies optical information from the information read out from the connected destination including information on optical capability indicating whether optical signals can be received by the connected destination of the first connector and optical connection information indicating successful reception of optical signals by the connected destination of the first connector, and - outputs optical information identified using both the information on optical capability and the optical connection information to the selection output controller; - identifies optical information from the information read out from the connected destination including information on optical capability indicating whether optical signals can be received by the connected destination of the first connector and optical connection information indicating successful reception of optical signals by the connected destination of the first connector, and - outputs optical information identified using both the information on optical capability and the optical connection information to the selection output controller; when the selection output controller determines to make an optical connection based on the optical information, the selection output controller outputs the AV signal using the optical output signals, and when the selection output controller determines to not make an optical connection based on the optical information, the selection output controller outputs the AV signal using the differential signals, and the AV signal output device is configured to supply and receive power through the first communications signal lines.