This method for producing an electrode catalyst includes: a dispersion liquid preparation step wherein a dispersion liquid is prepared by mixing (i) at least one solvent selected from the group consisting of sulfoxide compounds and amide compounds, (ii) a catalyst carrier powder composed of a metal oxide, (iii) a platinum compound, (iv) a transition metal compound and (v) an aromatic compound that contains a carboxyl group; a loading step wherein the dispersion liquid is heated so that a platinum alloy of platinum and a transition metal is loaded on the surface of the catalyst carrier powder; a solid-liquid separation step wherein a dispersoid is separated from the dispersion liquid after the loading step, thereby obtaining a catalyst powder wherein the catalyst carrier powder is loaded with the platinum alloy; and a heat treatment step wherein the catalyst powder is heated under vacuum or in a reducing gas atmosphere.