An organic light-emitting display device and a method of manufacturing the same. The organic light-emitting display device includes a first film formed of an inorganic material, a second film that is formed of an organic material and formed on the first film, and includes a first surface and a second surface facing each other and lateral surfaces at boundaries of the first surface and the second surface, with the first surface contacting the first film, a third film that is formed of an inorganic material and covers the second surface and lateral surfaces of the second film, with a first sealing region contacting the first film being formed at a boundary between the second film and the third film, an organic light-emitting unit that is disposed on the third film to overlap with the second film, and a fourth film that covers the organic light-emitting unit, with a second sealing region contacting the third film being formed at a boundary of the fourth film. Accordingly, the organic light-emitting display device is protected from water penetration, thereby providing a long life span to the organic light-emitting display device.