There is provided a method of manufacturing an electrode catalyst layer for fuel cell. This manufacturing method comprises: (a) separating an ionomer solution by centrifugation into a supernatant that includes only an ionomer as a low molecular-weight component in the ionomer solution and a sediment including an ionomer as a high molecular-weight component having a higher molecular weight than that of the low molecular-weight component included in the supernatant; (b) using the ionomer included in the sediment as an ionomer for electrode catalyst layer and producing a catalyst ink that includes catalyst-supported particles with a catalyst metal supported thereon, a solvent and the ionomer for electrode catalyst layer; and (c) using the catalyst ink to form an electrode catalyst layer.