Semiconductor device including through via structure and redistribution structures is provided. The semiconductor device may include internal circuits on a first side of a substrate, a through via structure vertically penetrating the substrate to be electrically connected to one of the internal circuits, a redistribution structure on a second side of the substrate and electrically connected to the through via structure, and an insulating layer between the second side of the substrate and the redistribution structure. The redistribution structure may include a redistribution barrier layer and a redistribution metal layer, and the redistribution barrier layer may extend on a bottom surface of the redistribution metal layer and may partially surround a side of the redistribution metal layer.