An organic light-emitting display device includes: a substrate; a display on the substrate and comprising a display region and a non-display region at a perimeter of the display region; a thin-film encapsulation layer sealing the display; a voltage line at the non-display region and surrounding the display region; and a dam unit overlapping an edge of an outer side of the voltage line, wherein the voltage line comprises: a first voltage line at one side of the display region; and a second voltage line surrounding a pair of first end portions of the first voltage line and other sides of the display region, and an outer side of the first voltage line and an outer side of the second voltage line are on a same line outside the one side of the display region.