An organic light-emitting display device is provided. The organic light-emitting display device includes: a substrate; a display unit on the substrate and includes a plurality of driving thin film transistors (TFTs) and a plurality of organic light-emitting diodes (OLEDs); and a sealing layer to cover the display unit which includes a first sealing layer that is formed of at least one inorganic layers to cover the plurality of OLEDs and a second sealing layer that is formed of at least one inorganic layers and at least one organic layers to enclose the plurality of OLEDs.