NOVELTY - Membrane/electrode assembly production comprises bonding a first gas diffusion layer (14), a first intermediate, and a second intermediate, so that a first catalyst layer (12) is located between the first gas diffusion layer and an electrolyte membrane (30), and a second catalyst layer (22) is located between a second gas diffusion layer (24) and the electrolyte membrane.    USE - For producing a membrane/electrode assembly for polymer electrolyte fuel cells used for power sources for mobiles such as automobiles, distributed power generation systems, and household cogeneration systems, or for methanol fuel cell.    ADVANTAGE - A high output voltage is obtainable within a wide range of current densities.    DETAILED DESCRIPTION - Membrane/electrode assembly production, where membrane/electrode assembly comprises a first electrode having a first catalyst layer and a first gas diffusion layer, a second electrode having a second catalyst layer and a second gas diffusion layer, and an electrolyte membrane interposed between the two electrodes, comprises applying a coating fluid containing an ion exchange resin on a substrate, followed by annealing at 100-250degreesC to form an electrolyte membrane, and applying a coating fluid containing an electrode catalyst and an ion exchange resin on the surface of the obtained electrolyte membrane to form the first catalyst layer, to prepare a first intermediate consisting of the electrolyte membrane and the first catalyst layer; applying a coating fluid containing an electrode catalyst and an ion exchange resin on the surface of the second gas diffusion layer to form the second catalyst layer, to prepare a second intermediate consisting of the second gas diffusion layer and the second catalyst layer; and bonding the first gas diffusion layer, the first intermediate, and the second intermediate, so that the first catalyst layer is located between the first gas diffusion layer and the electrolyte membrane, and the second catalyst layer is located between the second gas diffusion layer and the electrolyte membrane.    DESCRIPTION OF DRAWING(S) - The figure is a cross sectional view showing a polymer electrolyte fuel cell.    First catalyst layer (12)    First gas diffusion layer (14)    Second catalyst layer (22)    Second gas diffusion layer (24)    Electrolyte membrane (30)