A multimedia device connected with an external device, the multimedia device comprising: an external device interface module directly connecting the external device with the multimedia device; a network interface module configured to communicate with the external device through a network, wherein a communication path through the network interface module is different than a communication path through the external device interface module; a display module configured to display video data and first GUI data of the external device, which are received from the external device through the external device interface module; a user interface module configured to receive a control signal output from a remote controller; and characterized by a controller configured to process the control signal output from the remote controller in the multimedia device if second GUI data of the multimedia device are displayed on the display module together with the video data and the first GUI data, and transmit the processed control signal to the external device through the network interface module if the first GUI data of the external device are displayed but the second GUI data of the multimedia device are not displayed on the display module, wherein the controller is configured to control the display module to display a first indicator on the second GUI data, if coordinate value information calculated in accordance with a signal corresponding to motion of the remote controller corresponds to the second GUI data displayed on a screen of the display module, the controller is configured to control the display module to display a second indicator on the first GUI data, if coordinate value information calculated in accordance with a signal corresponding to motion of the remote controller corresponds to the first GUI data displayed on the screen of the display module, and the first indicator and the second indicator are different in at least one of shape, size, color, and transparency. an external device interface module directly connecting the external device with the multimedia device; a network interface module configured to communicate with the external device through a network, wherein a communication path through the network interface module is different than a communication path through the external device interface module; a display module configured to display video data and first GUI data of the external device, which are received from the external device through the external device interface module; a user interface module configured to receive a control signal output from a remote controller; and characterized by a controller configured to process the control signal output from the remote controller in the multimedia device if second GUI data of the multimedia device are displayed on the display module together with the video data and the first GUI data, and transmit the processed control signal to the external device through the network interface module if the first GUI data of the external device are displayed but the second GUI data of the multimedia device are not displayed on the display module, wherein the controller is configured to control the display module to display a first indicator on the second GUI data, if coordinate value information calculated in accordance with a signal corresponding to motion of the remote controller corresponds to the second GUI data displayed on a screen of the display module, the controller is configured to control the display module to display a second indicator on the first GUI data, if coordinate value information calculated in accordance with a signal corresponding to motion of the remote controller corresponds to the first GUI data displayed on the screen of the display module, and the first indicator and the second indicator are different in at least one of shape, size, color, and transparency.