Abstract: A thin-film solar cell includes a thin-film active layer with a p-n Junction and a heat-resistant substrate for mechanically supporting the active layer, which substrate is formed by a plasma coating method. In the plasma coating method, a source material of the substrate is melted with a high-temperature plasma and sprayed onto a base plate by a high-speed gas jet. Since the substrate formed by the plasma coating method is porous, even if an inexpensive material including a lot of impurities is used as a material of the substrate, the impurities are collected in pores of the substrate and never sprout out of the substrate breaking through the thin-film active layer.