MEMBRANE ELECTRODE ASSEMBLY, AND SOLID POLYMER ELECTROLYTE FUEL CELL

A membrane electrode assembly includes a polyelectrolyte membrane having a first surface and a second surface facing away from the first surface; a fuel-electrode-side electrocatalyst layer bonded to the first surface and containing a first catalytic material, a first electrically conductive carrier, and a first polyelectrolyte, the first electrically conductive carrier carrying the first catalytic material; and an oxygen-electrode-side electrocatalyst layer bonded to the second surface and containing a second catalytic material, a second electrically conductive carrier, a second polyelectrolyte, and a fibrous material, the second electrically conductive carrier carrying the second catalytic material. The membrane electrode assembly contains voids, the voids including pores each having a size in a range of 3 nm or more and 5.5 µm or less. A distribution curve indicating distribution of pore volume with respect to pore size has a peak at which the pore size is in the range of 0.06 µm or more and 0.11 µm or less, the pore volume being a total volume of pores having a specific pore size among the pores and being measured by mercury intrusion porosimetry, the pore size being a diameter of a pore calculated from the pore volume.