An organic light-emitting display device is provided. The organic light-emitting display device includes an upper substrate coupling a lower substrate by an encapsulating layer. The upper substrate includes a metal. An inclined surface is formed at an edge of a substrate of the upper substrate by a rotating polishing wheel. Thus, in the organic light-emitting display device, the reliability may be prevented from being decreased by the metal burr without lowering the process efficiency and uniformity.