A method of fabricating a motheye mold according to the present invention includes the steps of: (a) anodizing a surface of an aluminum film (10a) via an electrode (32a) that is in contact with the surface, thereby forming a porous alumina layer which has a plurality of very small recessed portions; (b) after step (a), allowing the porous alumina layer to be in contact with an etchant, thereby enlarging the very small recessed portions of the porous alumina layer; and (c) after step (b), further anodizing the surface to grow the plurality of very small recessed portions. The aluminum film is made of aluminum with a purity of 99.99 mass % or higher. The electrode includes a first electrode portion (32a1) which is made of aluminum with a purity of 99.50 mass % or lower and a second electrode portion (32a2) which is made of aluminum with a higher purity than the aluminum of the first electrode portion and which is interposed between the surface and the first electrode portion. Step (a) and step (c) are performed with the second electrode portion being in contact with the surface in an electrolytic solution. According to the present invention, a method of efficiently anodizing an aluminum film formed over a large surface substrate and an electrode structure for use in the method.