Membrane electrode assembly

A membrane electrode assembly comprising:

• a polymer electrolyte membrane;
• an anode catalyst layer disposed on one surface of the polymer electrolyte membrane;
• and
• a cathode catalyst layer disposed on the other surface of the polymer electrolyte membrane,
• wherein the membrane electrode assembly contains a nitrogen-containing multidentate ligand capable of coordinating to metal ions,
• wherein the cathode catalyst layer includes an electrode catalyst and an ionomer,
• wherein the electrode catalyst is a metal-supported catalyst in which metal particles having catalytic activity are supported on a support having pores, and
• wherein, when metal particles present on outermost surfaces of primary particles of the support are external particles, and metal particles present inside the outermost surfaces of the primary particles of the support are internal particles, a ratio of a total particle count of the external particles to a total particle count of the internal particles (total particle count of external particles/total particle count of internal particles) is 0.70 or less.