Provided is an organic electroluminescent display device, including a substrate, an organic light-emitting device on the substrate, and an encapsulation layer formed on the organic light-emitting device and the substrate. The encapsulation layer includes an inorganic layer and a polymer organic layer alternatingly stacked with an intermediate layer formed of a first organic monomer between the inorganic layer and the polymer organic layer, and one surface of the intermediate layer is bonded to the inorganic layer through bonding sites on a surface of the inorganic layer and another surface of the intermediate layer is bonded to the organic layer by polymerization.