A transparent display device includes an image display bar in which a plurality of light-emitting elements are arranged, and a bar driving unit which moves the image display bar along a predetermined path and provides transparent display using afterimages resulting from the movement of the light-emitting elements, wherein the transparency of the transparent display using afterimages is determined by the equation, transparency (%)=((A−B)/A)*100, where A denotes the entire display area of the transparent display, and B denotes the area of the image display bar.