A method of manufacturing a tandem-type thin film photoelectric conversion device includes the steps of forming at least one photoelectric conversion unit (3) on a substrate (1) in a deposition apparatus, taking out the substrate (1) having the photoelectric conversion unit (3) from the deposition apparatus to the air, introducing the substrate (1) into a deposition apparatus and carrying out plasma exposure processing on the substrate (1) in an atmosphere of a gas mixture containing an impurity for determining the conductivity type of the same conductivity type as that of the uppermost conductivity type layer (33) and hydrogen, forming a conductivity type intermediate layer (5) by additionally supplying semiconductor raw gas to the deposition apparatus, and then forming a subsequent photoelectric conversion unit (4).