TECHNOLOGY FOCUS - POLYMERS - Preferred Component: The second slurry and catalyst paste comprise a pore-forming material. The polymer electrolyte membrane is formed from sulfonated polyarylene based polymer solution. The catalyst paste comprises catalyst particles having catalyst supported with carbon particles, organic solvent solution having perfluoroalkylene sulfonic acid polymer, and pore-forming material.Preferred Process: The electrode catalyst layer is dried to an extent that the content of the solvent becomes at most 20 wt.% based on total weight of the electrode catalyst layer. The dried electrode catalyst layer is thermal transferred and connected to the polymer electrolyte membrane. The catalyst paste is applied on the sheet substrate whose surface has a contact angle of 55-105 degrees. The diffusion electrode is laminated on each electrode catalyst layer, and pressed under heating. The applied pressure is 0.5-4 MPa.Preferred Ratio: The hydrophilic layer and electrode catalyst layer are formed so that the ratio of the volume of pores with a pore size of 0.01-1 micrometer in the electrode catalyst layer by the pore-forming material to the volume of pores with a pore size of 0.01-1 micrometer formed in the hydrophilic layer by pore-forming material is less than 1. The hydrophilic layer and electrode catalyst layer are formed so that the ratio of the weight of the ion conducting material contained in the electrode catalyst layer to the weight of the ion conducting material contained in the hydrophilic layer is 1-1.4. The hydrophilic layer and electrode catalyst layer are formed so that the ratio of the weight of the solid content in the electrode catalyst layer to the weight of solid content in hydrophilic layer is 1-3.5. The hydrophilic layer is formed so that is has a surface roughness where the ratio of the surface area to the unit area is at most 1.25.Preferred Property: The hydrophilic layer has a maximum height of surface roughness (Rmax) of at most 40 micrometers. The water-repellent layer and hydrophilic layer are formed so that the differential pressure between one side of the diffusion electrode and its other side is between 100-300 mmAq when the air is supplied at a flow rate of 0.5 L/cm2/min in the direction of the thickness of the diffusion electrode. The thermal transfer is carried out under a pressure of 1-5 MPa.