A display device including: a display module including a display folding portion and a display curved portion adjacent to the display folding portion, wherein the display curved portion has a curvature when the display folding portion is folded; and a window disposed on the display module, the window including a first surface and a second surface opposite to the first surface, and having first grooves overlapping the display folding portion and second grooves overlapping the display curved portion, wherein the first grooves are formed in the first surface of the window and the second grooves are formed in the second surface of the window.