A display device includes: a substrate; a buffer layer on the substrate; a first active pattern and a second active pattern on the buffer layer and spaced apart from each other; a first gate insulation layer on the first active pattern and the second active pattern; a first gate electrode and a second gate electrode on the first gate insulation layer, the first gate electrode and the second gate electrode respectively overlapping the first active pattern and the second active pattern; a second gate insulation layer on the first gate electrode and the second gate electrode; and a capacitor electrode on the second gate insulation layer, the capacitor electrode overlapping the first gate electrode, wherein a permittivity of the first gate insulation layer is greater than a permittivity of the buffer layer.