A remote controller applied to a display device includes a wireless communication element, a voice receiving and transmitting element and a control unit. The wireless communication element is utilized for performing a wireless communication with a set-up box of the display device. The control unit is coupled to the wireless communication element and the voice receiving and transmitting element, and is utilized for controlling a voice communication between the wireless communication element and the set-up box. When the remote controller does not need to have the voice communication and any other communication with the set-up box, the control unit disables the wireless communication element to make the wireless communication element be unable to receive and process any information from the set-up box.