NOVELTY - A catalyst substance or carbon particle is dispersed to the solvent with peroxide decomposition catalyst and primary polymer electrolyte, to obtain primary catalyst ink. The primary catalyst ink is dried and catalyst substance, peroxide decomposition catalyst, or carbon particle and peroxide decomposition catalyst are embedded with a primary polymer electrolyte and secondary polymer electrolyte, to obtain secondary catalyst ink. The secondary catalyst ink is coated on the base material, and electrode catalyst layer is formed, to obtain fuel cell electrode catalyst layer.    USE - Manufacture of fuel cell electrode catalyst layer used for manufacturing fuel cell membrane electrode assembly for polymer electrolyte fuel cell (all claimed).    ADVANTAGE - The fuel cell electrode catalyst layer has high power generation characteristics and durability, and is efficiently manufactured with suppressed damage to the electrode catalyst, and improved proton conductivity and output performance.    DETAILED DESCRIPTION - A catalyst substance or carbon particle is dispersed to the solvent with peroxide decomposition catalyst and primary polymer electrolyte, to obtain primary catalyst ink. The primary catalyst ink is dried and catalyst substance, peroxide decomposition catalyst, or carbon particle and peroxide decomposition catalyst are embedded with a primary polymer electrolyte. The carbon particle or catalyst substance is added to the primary catalyst ink dry-processed at the secondary process. Then, the catalyst substance, carbon particle, peroxide decomposition catalyst and primary polymer electrolyte are dispersed to the solvent with the secondary polymer electrolyte, to obtain secondary catalyst ink. The secondary catalyst ink is coated on the base material chosen from a gas diffusion layer, a transfer sheet and a polymer electrolyte membrane, and electrode catalyst layer is formed, to obtain fuel cell electrode catalyst layer. INDEPENDENT CLAIMS are included for the following:    (1) fuel cell electrode catalyst layer;    (2) manufacture of fuel cell membrane electrode assembly;    (3) fuel cell membrane electrode assembly; and    (4) polymer electrolyte fuel cell.    DESCRIPTION OF DRAWING(S) - The drawing shows the schematic view of membrane electrode assembly.    Solid polymer electrolyte membrane (1)    Electrode catalyst layer (2)    Electrode catalyst layer (3)    Membrane electrode assembly (12)