NOVELTY - The organic thin-film solar cell comprises a metal electrode layer (1), an electron extraction layer (2) such as a zinc oxide layer, a photoelectric conversion layer (3), and a transparent electrode layer (5). The metal electrode layer includes an aluminum layer on a surface of the electrode layer. The electron extraction layer: is formed on the aluminum layer of the metal electrode layer; and has a concentration gradient in which a content of an oxygen atom in the electron extraction layer tends to increase from the metal electrode layer side to the photoelectric conversion layer.    USE - Used as an organic thin-film solar cell.    ADVANTAGE - The organic thin-film solar cell can be economically and easily manufactured with high performance, increased conversion efficiency and improved stability.    DETAILED DESCRIPTION - The organic thin-film solar cell comprises a metal electrode layer (1), an electron extraction layer (2) such as a zinc oxide layer, a photoelectric conversion layer (3), and a transparent electrode layer (5). The metal electrode layer includes an aluminum layer on a surface of the electrode layer. The electron extraction layer: is formed on the aluminum layer of the metal electrode layer; has a concentration gradient in which a content of an oxygen atom in the electron extraction layer tends to increase from the metal electrode layer side to the photoelectric conversion layer; and contains a zinc layer placed at a surface of the metal electrode layer side. The photoelectric conversion layer is formed on the electron extraction layer. The transparent electrode layer is formed on the photoelectric conversion layer. A surface of the metal electrode layer, on which the electron extraction layer is formed, has an arithmetic mean surface roughness of less than or equal to 5 mu m. An INDEPENDENT CLAIM is included for a method for manufacturing an organic thin-film solar cell.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic cross-sectional view of an organic thin-film solar cell.    Metal electrode layer (1)    Electron extraction layer (2)    Photoelectric conversion layer (3)    Hole extraction layer (4)    Transparent electrode layer. (5)