Provided are an organic light-emitting display device and a method of manufacturing the organic light-emitting display device, the method including operations of forming pattern layers in an active area and a pad area, respectively, on a substrate; and forming an encapsulation thin-film layer that covers the pattern layers on the substrate, wherein the operation of the encapsulation thin-film layer may include an operation of forming the encapsulation thin-film layer on the substrate by using a raw material of the encapsulation thin-film layer that is a single layer comprising an inorganic material.