A display device includes a base substrate including a display area and a non-display area around the display area are defined, a first interlayer insulating layer disposed on the base substrate, a second interlayer insulating layer disposed on the first interlayer insulating layer, a first semiconductor layer disposed on the second interlayer insulating layer and including an oxide, and a first gate insulating layer disposed on the first semiconductor layer, wherein the material of the first interlayer insulating layer and the material of the second interlayer insulating layer are different from each other. Methods of manufacturing a display device are also disclosed.