Abstract: A display device includes a substrate, a pixel driver on the substrate, and a display element connected to the pixel driver. The pixel driver includes a conductive layer on the substrate, a buffer layer on the conductive layer, a semiconductor layer on the buffer layer, a gate electrode, the gate electrode overlapping the semiconductor layer, and a source electrode and a drain electrode connected to the semiconductor layer. The buffer layer includes a flattened portion overlapping the conductive layer, and a stepped portion overlapping the periphery of the conductive layer. The semiconductor layer includes a first oxide semiconductor layer on the buffer layer, and a second oxide semiconductor layer on the first oxide semiconductor layer. A width of the first oxide semiconductor layer is larger than a width of the second oxide semiconductor layer, and the first oxide semiconductor layer is on the stepped portion of the buffer layer.