A display device includes a window combined with a substrate. The substrate includes a display region with pixels and a non-display region with power lines for the pixels. The window includes a display part corresponding to the display region and a non-display part corresponding to the non-display region. A plurality of alignment marks are on the substrate at a location corresponding to the non-display region. The alignment marks are integrally provided with an outermost power line at an outermost side of the non-display region, and each of the alignment marks overlaps with the non-display part of the window.