A membrane electrode assembly is prepared by sandwiching an electrolyte membrane between an anode and a cathode. In the anode, a first porous layer is interposed between a first electrode catalyst layer and a first gas diffusion layer. In the cathode, a second porous layer is interposed between a second electrode catalyst layer and a second gas diffusion layer. A first piled body of the first gas diffusion layer and the first porous layer has a percolation pressure higher than that of a second piled body containing the second gas diffusion layer and the second porous layer. The first piled body has a percolation pressure of 25 to 120 kPa, and the second piled body has a percolation pressure of 5 to 25 kPa.