A method for controlling a display device that displays a frame buffer on a plurality of screens is provided. The method includes receiving a multi-screen mode execution command to display a single frame buffer on a plurality of screens, acquiring the frame buffer, splitting the frame buffer into a plurality of frame buffers to correspond to the plurality of screens, setting an offset for each of the plurality of split frame buffers, and displaying each of the plurality of split frame buffers on an associated one of the plurality of screens based on the set offset.