A display device includes a substrate, a corrosion prevention layer on the substrate and including an inorganic material, a first conductive layer on the corrosion prevention layer and including aluminum or an aluminum alloy, a first insulating film on the first conductive layer, a semiconductor layer on the first insulating film and including a channel region of a transistor, a second insulating film on the semiconductor layer, and a second conductive layer on the second insulating film and including a barrier layer, which includes titanium, and a main conductive layer, which includes aluminum or an aluminum alloy, wherein the semiconductor layer includes an oxide semiconductor, and the barrier layer is between the semiconductor layer and the main conductive layer and overlaps the channel region of the transistor.