NOVELTY - Catalyst substance or carbon particles and polymer electrolyte (A) are dispersed in solvent, to obtain catalyst ink (A). The obtained ink (A) is dried and polymer electrolyte is embedded in catalyst substance or carbon particles. Then, the polymer electrolyte embedded in catalyst substance or carbon particles, and polymer electrolyte (B) are dispersed in solvent, to obtain catalyst ink (B). The obtained ink (B) is coated on base material chosen from gas diffusion layer, transfer sheet and polymer electrolyte membrane (1), to obtain electrode catalyst layer (2,3).    USE - Manufacture of electrode catalyst layer used for manufacture of fuel cell membrane electrode assembly for polymer electrolyte fuel cell (all claimed) used as power supply for vehicle and domestic appliances.    ADVANTAGE - Since the electrode catalyst layer is formed using oxide-based non-platinum catalyst as catalyst substance, the electrode catalyst layer has high power generation characteristics. The proton conductivity on surface of catalyst is improved during formation of electrode catalyst layer, by adjusting the specific surface area of carbon particles.    DETAILED DESCRIPTION - Catalyst substance or carbon particles and polymer electrolyte (A) are dispersed in solvent, to obtain catalyst ink (A). The obtained catalyst ink (A) is dried and polymer electrolyte is embedded in catalyst substance or carbon particles. Then, the polymer electrolyte embedded in catalyst substance or carbon particles, and polymer electrolyte (B) are dispersed in solvent, to obtain catalyst ink (B). The obtained catalyst ink (B) is coated on base material chosen from gas diffusion layer, transfer sheet and polymer electrolyte membrane, to obtain electrode catalyst layer. The specific surface area of catalyst substance is lesser than that of the carbon particles. INDEPENDENT CLAIMS are included for the following:    (1) manufacture of membrane electrode assembly;    (2) membrane electrode assembly (12); and    (3) polymer electrolyte fuel cell.    DESCRIPTION OF DRAWING(S) - The drawing shows cross-sectional view of membrane electrode assembly.    Solid polymer electrolyte membrane (1)    Electrode catalyst layers (2,3)    Membrane electrode assembly (12)