An organic light-emitting display device includes a substrate including an active area in which a plurality of pixels are defined, and a non-active area surrounding the active area and having a pad area in which a plurality of pads are disposed on one side of the active area; a plurality of power supply lines disposed in the active area; a plurality of test transistors disposed in the non-active area on another side of the active area; and a plurality of power supply transistors connected to the plurality of power supply lines. Each of the power supply transistors is disposed next to the respective test transistors. A uniform supply voltage can thus be applied across a plurality of pixels without any additional process such that uniformity of luminance can be improved.