A display device includes a base substrate, a buffer layer disposed on the base substrate, an active layer disposed on the buffer layer, a first gate insulation layer disposed on the active layer, a first conductive layer disposed on the first gate insulation layer and which is a single-layer including an aluminum alloy, a second gate insulation layer disposed on the first conductive layer, a second conductive layer disposed on the second gate insulation layer and which is a single-layer including an aluminum alloy, an insulation interlayer disposed on the second conductive layer, and a third conductive layer disposed on the insulation interlayer, directly contacting the first conductive layer through a first gate contact hole defined in the insulation interlayer and the second gate insulation layer, and directly contacting the second conductive layer through a second gate contact hole defined in the insulation interlayer.