An organic light-emitting display device including a substrate including a display area and a non-display area; a thin film transistor disposed on the substrate in the non-display area; an electroluminescent device disposed in the display area; and an overcoat layer disposed on the substrate and including two or more concave portions and two or more convex portions in the display area. Further, the two or more concave portions and the two or more convex portions form a linear pattern in a plan view. In addition, the electroluminescent device includes a first electrode disposed on the overcoat layer and connecting the electroluminescent device to the thin film transistor; an organic light-emitting layer disposed on the first electrode and configured to emit light; and a second electrode disposed on the organic light-emitting layer. Also, the linear pattern of the two or more concave portions and the two or more convex portions comprise one of a zigzag pattern, a streamlined pattern, and combinations thereof.