NOVELTY - A film catalyst layer joint-component has a polymeric electrolyte film (11) interposed between a cathode catalyst layer (12a) and an anode catalyst layer (12b). In the cathode catalyst layer, the ratio of mass of polyelectrolyte to the mass of catalyst-supporting carbon decreases from the innermost layer nearest to the polymeric electrolyte film to the outermost layer farthest from the polymeric electrolyte film. The ratio in the innermost layer is 0.8-3, and the ratio in the outermost layer is 0.2-0.6.    USE - Used for a membrane-electrode joint-component used in polyelectrolyte-type fuel cells (both claimed) used for mobile components, distribution electric-power-generation systems, domestic co-generation systems, and motor vehicles.    ADVANTAGE - The film catalyst layer joint-component provides polyelectrolyte-type fuel cells having good initial characteristics, cell performance, and durability.    DETAILED DESCRIPTION - The film catalyst layer joint component has a polymeric electrolyte film (11) having hydrogen-ion conductivity, interposed between a cathode catalyst layer (12a) and an anode catalyst layer (12b). The catalyst layers contain catalyst-supporting carbon comprising an electrode catalyst supported by carbon powder. The polyelectrolyte is adhered to the catalyst-carrying carbon. The cathode catalyst layer comprises at least two layers. In the cathode catalyst layer, the ratio (Wp/WCat-C) of the mass (Wp) of the polyelectrolyte to the mass (WCat-C) of the catalyst-supporting carbon decreases from the innermost layer nearest to the polymeric electrolyte film to the outermost layer farthest from the polymeric electrolyte film. The ratio in the innermost layer is 0.8-3, and the ratio in the outermost layer is 0.2-0.6.    INDEPENDENT CLAIMS are also included for the following:    (1) a membrane-electrode joint-component (10); and    (2) a polyelectrolyte-type fuel cell (1).    DESCRIPTION OF DRAWING(S) - The figure shows an outline sectional drawing of the polyelectrolyte-type fuel cell.    polyelectrolyte-type fuel cell (1)    membrane-electrode joint-component (10)    polymeric electrolyte film (11)    cathode catalyst layer (12a)    anode catalyst layer (12b)