A display device includes a display panel which includes first and second display areas adjacent to each other, a processor which generates first image data corresponding to the first and second display areas if a display mode is a first mode, and generates second image data corresponding to the first display area if the display mode is a second mode and a display driver which generates a first data signal corresponding to the first image data in the first mode, and converts the second image data and generates a second data signal corresponding to the converted second image data in the second mode. When the display device is driven in the second mode, a gradation image may be displayed on at least a region of the second display area.