TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Properties: The porosity of the hydrophilic porous layer is more than the porosity of the catalyst layer. The BrunauerEmmettTeller nitrogen specific surface area of electroconductive material in the hydrophilic porous layer is less than the BrunauerEmmettTeller nitrogen specific surface area of electrode catalyst in the catalyst layer. The thickness of the hydrophilic porous layer is less than the catalyst layer. The effective diffusion coefficient (A) (m2/second) of steam in the gas diffusion-layer base material satisfies the relation: A is more than 2x 10-5x s(power)(c), where s is porosity of gas diffusion-layer base material and c is zigzag coefficient of gas diffusion-layer base material. The diameter of minimum hole in the gas diffusion-layer base material is 1 mu m or more. The ion-conductive material has equivalent weight of 1000 g/eq or less. The coating area of electroconductive material covered by the ion-conductive material comprising liquid water-evaporation stimulation material is 200 m2/g or more. The coating area of electroconductive material covered by the ion-conductive material comprising liquid water-transport stimulation material is 200 m2/g or less. Preferred Arrangement: The hydrophilic porous layer is provided between catalyst layer and gas diffusion layer in the membrane electrode assembly. At least one portion of hydrophilic porous film is formed inside the gas diffusion layer. At least one portion of hydrophilic porous film is provided to gas diffusion-layer base material. At least one portion of gas diffusion-layer base material has hydrophilic processed portion. The gas diffusion layer is provided in pole of anode (11) of the membrane electrode assembly. The electroconductive material is covered by the ion-conductive material such that the coating area of ion-conductive material is product of BrunauerEmmettTeller nitrogen specific surface area of electroconductive material and ion-conductive material coverage. The gas diffusion electrode has layer structure comprising a layer containing liquid water-evaporation stimulation material and a layer containing liquid water-transport stimulation material, or comprises liquid water-evaporation stimulation material and liquid water-transport stimulation material in mixed state in the hydrophilic porous layer. The membrane electrode assembly has structure in which sparse of portion which opposes a cathode gas outlet of the hydrophilic porous layer is more than the portion which opposes the cathode gas inlet of the hydrophilic porous layer. Preferred Composition: The catalyst layer contains electroconductive carrier which supports ion-conductive material and catalyst component. The catalyst layer has structure which forms conveyance path of continuous liquid water, when both the ion-conductive material contact. The electroconductive carrier comprises graphitized carbon material. A portion which opposes cathode gas outlet of the hydrophilic porous layer has content of liquid water-evaporation stimulation material more than the content of liquid water-transport stimulation material, or content of liquid water-transport stimulation material more than the content of liquid water-evaporation stimulation material. Preferred Process: Alternately, the gas diffusion electrode is manufactured by coating the catalyst ink containing electrode catalyst, ion-conductive material and solvent on electrolytic membrane, coating hydrophilic porous film-forming slurry containing electroconductive material, ion-conductive material and solvent, and hot pressing surface of gas diffusion-layer base material to which solution containing hydrophilic agent is coated, and surface to which hydrophilic porous film-forming slurry is coated. The membrane electrode assembly is manufactured by integrating gas diffusion layer on opposite side to the catalyst layer. The ink containing high-boiling-point organic solvent having boiling point of 150 degrees C is coated to form membrane electrode assembly.    TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: The hydrophilic processed portion in the gas diffusion electrode contains ion-conductive material, metal oxide and hydrophilic polymer.