To provide a photovoltaic device improved in interface characteristics, and a manufacturing method thereof.

An amorphous semiconductor device is equipped with amorphous semiconductor layers 3 and 4, which are different from each other in conductivity-type, adjacent to each other in the vertical direction, and formed on a substrate 1, where a natural oxide layer b formed of a natural oxide of a main element contained in the amorphous semiconductor layer 3 arranged closer to the substrate 1 than the semiconductor layer 4 is provided between the adjacent amorphous semiconductor layers 3 and 4.