To provide a membrane/electrode assembly for polymer electrolyte fuel cells, capable of achieving high power generation performance under low or no humidity operation conditions, and a process for producing a cathode for polymer electrolyte fuel cells. A membrane/electrode assembly 10, comprising: an anode 20 having a catalyst layer 22 and a gas diffusion layer 28, a cathode 30 having a catalyst layer 32 and a gas diffusion layer 38, and a polymer electrolyte membrane 40 interposed between the catalyst layer 22 of the anode 20 and the catalyst layer 32 of the cathode, wherein the cathode 30 has, between the catalyst layer 32 and the gas diffusion layer 38, a first interlayer 36 comprising carbon fibers (C1) and a fluorinated ion exchange resin (F1), and a second interlayer 34 comprising carbon fibers (C2) and a fluorinated ion exchange resin (F2), in this order from the gas diffusion layer 38 side.