NOVELTY - A fuel cell membrane-electrode assembly has a fuel electrode (4) at one surface side of an electrolyte membrane (1), and an oxidant electrode at another surface side of the membrane. At least one of the fuel electrode and the oxidant electrode comprises a non-supported-catalyst containing catalyst layer (2) that contains a metal catalyst nanoparticle (8) of 0.3-100 (preferably 5-10) nm in primary particle diameter that is not supported on a support. An electrochemically active surface area of the nanoparticle is 10-150 m2/g. A layer thickness of catalyst layer is less than or equal to10 or less than or equal to5 microns.    USE - For fuel cells as a portable power source or power source of mobile bodies.    ADVANTAGE - The cell exhibits excellent resistance to an abnormally high potential state in the oxidant electrode. The invention restrains the decline of the durability of a fuel cell caused by the oxidation corrosion of a support that supports a catalyst. The assembly is high in the catalyst utilization rate, and is excellent in the gas diffusivity, the proton conductivity and the electrical conductivity, and can deliver excellent power generation performance. It enables cost reduction of the fuel cell. The fuel cell is excellent in durability as well as in power generation performance.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a production method for a fuel cell membrane-electrode assembly by forming a non-supported-catalyst containing layer arranged on at least one of the fuel electrode side and the oxygen electrode side, by using a catalyst ink that contains a metal catalyst nanoparticle having a primary particle diameter of 0.3-100 nm and not supported on a support, an electrolyte resin, and a water-based solvent. The metal catalyst nanoparticle is a platinum particle. The non-supported-catalyst containing catalyst layer contains a carbon particle (preferably highly crystallized carbon) that is a water-repellent particle and that has surface area of 5-200 m2/g. An amount of the metal catalyst nanoparticle per unit area of the non-supported-catalyst containing catalyst layer is 0.001-10 mg/cm2.    DESCRIPTION OF DRAWING(S) - The figure is an enlarged partial view of a cell.    Electrolyte membrane (1)    Non-supported-catalyst containing catalyst layer (2)    Electrode (4)    Metal catalyst nanoparticle (8)    Electrolyte resin (11)