A membrane-electrode assembly for a direct oxidation fuel cell includes an electrolyte membrane, and an anode and a cathode sandwiching said electrolyte membrane. The cathode includes a catalyst layer in contact with the electrolyte membrane and a diffusion layer formed on the catalyst layer, and the catalyst layer contains 2 to 20% by volume of pores. A direct oxidation fuel cell including this membrane-electrode assembly has excellent power generating performance and durability.