An organic light-emitting display device can include 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, in which the two or more concave portions and the two or more convex portions form a plan-view pattern including one of a polygonal pattern having same centers, a polygonal pattern having different centers, a circular pattern having same centers, a circular pattern having different centers, an oval pattern having same centers, an oval pattern having different centers, a spiral pattern, and combinations thereof, and 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.