A display device includes a substrate including a display area and a driving circuit area, a first transistor in the display area, and including a first active layer on the substrate and a first gate electrode on the first active layer, a first gate insulating layer between the first active layer and the first gate electrode, and entirely covering the first active layer, a second transistor in the driving circuit area, and including a second active layer on the substrate and a second gate electrode on the second active layer, a second gate insulating layer between the second active layer and the second gate electrode, covering a part of the second active layer overlapping the second gate electrode, and exposing another part of the second active layer, and a first oxide semiconductor layer between the first gate insulating layer and the first gate electrode.