An organic light emitting diode display according to an exemplary embodiment includes: a substrate; a first buffer layer on the substrate; a first semiconductor layer on the first buffer layer; a first gate insulating layer on the first semiconductor layer; a first gate electrode and a blocking layer on the first gate insulating layer; a second buffer layer on the first gate electrode; a second semiconductor layer on the second buffer layer; a second gate insulating layer on the second semiconductor layer; and a second gate electrode on the second gate insulating layer.