The inventive concept relates to a display device and a driving method thereof. A display device according to an exemplary embodiment of the inventive concept includes: a display panel including a plurality of pixels and a plurality of data lines; a data driver applying data voltages to the plurality of data lines; a signal controller controlling the data driver; and a graphic controller inputting an image signal that is dithered based on dithering patterns of one set to the signal controller, wherein the signal controller includes a dithering cycle detector configured to detect a dithering cycle which is a cycle in which the dithering patterns of one set are repeated, and a still image detector configured to determine whether a current frame is a frame displaying a still image or a frame displaying a motion picture image based on the dithering cycle and the image signal.