A method for producing a catalyst-layer-supporting substrate includes a lamination step of forming a laminate of metal catalyst layers and mixture layers on a substrate by repeating a first step and a second step plural times alternatively; and an acid treatment step of subjecting the laminate to an acid treatment, wherein the first step is a step of sputtering or depositing the metal catalyst layer that comprises a catalyst, and the second step is a step of sputtering or depositing the mixture layer of carbon and metal, the metal of the mixture layer including at least one element M selected from the group consisting of Sn, Al, Cu and Zn.