Abstract: A method for producing an alloy catalyst for redox reaction comprising alloy particles of platinum and nickel, wherein the alloy particles are equipped at an outer surface with a crystal lattice plane represented by a Miller index {111} and have an average particle diameter in a range of 6 to 20 nm, the method comprising: dissolving, in an alcohol, a salt and/or complex of platinum, a salt and/or complex of nickel, and a polymer containing a plurality of salt structures comprising an organic cation and a halogen anion in a polymer chain and heating the resulting solution to reflux under an inert atmosphere.