Electroluminescence elements mounted on a substrate of an OLED display device are sealed by a protective film made of synthetic resin with chemical reaction curing in place of a sealing can. The protective film is formed such that a thickness thereof is equal to or larger than a thickness of the substrate. Alternatively, the protective film is formed by laminating a plurality of resin films which differ in one of the water absorption ratio, the elastic modulus and the hardness. With respect to the protective film which is formed of a plurality of laminated films, compared to the protective film at the electroluminescence element side, the protective film which covers the former protective film has the water absorption ratio, the elastic modulus or the hardness larger than the water absorption ratio, the elastic modulus or the hardness of the former protective film. Due to such a constitution, it is possible to reduce the thickness of the OLED display device without damaging the moisture-proof property of the electroluminescence elements.