An organic light-emitting display device. A substrate is divided into a plurality of subpixels generating different colors of light. A light leakage prevention layer is disposed on a portion of the substrate corresponding to a light-emitting area of at least one subpixel of the plurality of subpixels. An overcoat layer is disposed on a portion of the substrate corresponding to at least one subpixel of the plurality of subpixels, and includes microlenses having a plurality of concave portions or a plurality of convex portions. An organic electroluminescent device is disposed on the overcoat layer.