A manufacturing method of a photovoltaic device, whereby a photovoltaic device of a large area in the laminated structure of a first resin layer with light- transmitting property, a photo-electric converting element consisting of a transparent electrode layer, a thin-film semiconductor layer and a back electrode layer, and a second resin layer in this order is mechanically cut into an optional size, which is followed by a step wherein the first and second resin layers of the cut photovoltaic device of a smaller area are thermally treated or at least one of the transparent electrode layer and back electrode layer at the section is etched and removed. Because of the above treatment for the cut photovoltaic device of a smaller area, an electric short circuit between the transparent electrode layer and back electrode layer at the section is prevented.