This invention provides a process for producing a membrane electrode assembly which has high and stable catalytic activity, and suppressed deterioration in catalytic activity during operation, and can prevent a deterioration in performance attributable to a structural factor of the membrane electrode assembly. The process comprises the step of, after the washing/removing step, drying the catalyst electrode in an atmosphere having a lower oxygen partial pressure than the air. The anode/cathode is a covered catalyst electrode having a structure formed by supporting/depositing a catalytically active material composed mainly of platinum/ruthenium subjected to the potential holding step, the washing/removing step, and the drying step, on a porous electroconductive carrier to cover at least a part of the porous electroconductive carrier with the ion conductive material.