In a display system, a wireless transmitter receives video data and a CEC command from an AV amplifier, determines whether the received CEC command is a preset command or not, generates a confirmation command if it is determined that the CEC command is a preset command, and transmits the video data and the CEC command received from the AV amplifier and the confirmation command, to a projector. The projector receives the video data, the CEC command and the confirmation command transmitted from the wireless transmitter, and determines whether the received CEC command and confirmation command correspond to each other or not.