A display device including: an image determiner configured to determine whether a still image is displayed by comparing first partial image data that is a portion of image data of a previous frame with second partial image data that is a portion of image data of a current frame at a first time of a first mode in which a non-moving image is displayed, and determine whether the still image is displayed by comparing first frame data that is all image data of a previous frame with second frame data that is all image data of a current frame at a second time of a second mode in which a moving image is displayed; a display panel including pixels that receive a data signal corresponding to image data; and a panel driver configured to change a frequency at which the pixels are driven according to the first and second modes.