An organic light-emitting display device includes: a substrate; an active layer on the substrate; a gate electrode insulated from the active layer and overlapping with the active layer; a source electrode including a first source electrode layer, connected to the active layer, and a second source electrode layer connected to the first source electrode layer, the second source electrode layer being larger than the first source electrode layer; a drain electrode including a first drain electrode layer connected to the active layer, and a second drain electrode layer connected to the first drain electrode layer, the second drain electrode layer being larger than the first drain electrode layer; a first electrode directly connected to a top surface of the source electrode or the drain electrode; an intermediate layer on the first electrode and including an organic emission layer; and a second electrode on the intermediate layer.