An organic light-emitting display device includes a substrate and a display area over the substrate. The display area includes a plurality of organic light-emitting diodes each including a first electrode, an emission layer, and a second electrode. A first power supply line is located outside the display area and is configured to supply power to the plurality of organic light-emitting diodes. A protective portion is disposed on an end of the first power supply line facing away from the display area. An encapsulation unit includes a first inorganic encapsulation layer, an organic encapsulation layer, and a second inorganic encapsulation layer. The encapsulation unit is positioned in the display area. A dam unit is arranged between the first inorganic encapsulation layer and the second inorganic encapsulation layer. The dam unit is disposed on an end of the organic encapsulation layer facing away from the display area.