A display device comprises a substrate including display and peripheral areas, a semiconductor element, a pixel structure, and a plurality of dummy patterns. The semiconductor element is disposed in the display area on the substrate, and the pixel structure is disposed on the semiconductor element. The dummy patterns which have stacked structure are disposed in the peripheral area on the substrate, and contain a material identical to a material constituting the semiconductor element. The dummy patterns are arranged in a grid shape in different layers, and each of the dummy patterns includes a central portion and an edge portion surrounding the central portion. The edge portions of dummy patterns which are adjacent to each other in the different layers among the dummy patterns are overlapped each other in a direction from the substrate to the pixel structure.