Discloses herein is a method and apparatus for processing video data of a display device in which dithering noise generating when a motion picture is displayed can be minimized. According to the present invention, the method of processing the video data of the display device includes the steps of comparing data of an ith frame (i is a natural number) and data of a (i+1)th frame to determine whether the data of the (i+1)th frame is a motion picture or a still image, and employing a different dithering method depending upon the determination result of the motion picture or the still image.