To provide a membrane and electrode assembly comprising a catalyst layer that improves water holding properties and exhibits high power generation characteristics even in low humidified conditions without inhibiting the diffusibility of reaction gas, the removal of the water generated by the electrode reaction, and its manufacturing method. There is provided a membrane and electrode assembly produced by sandwiching a polymer electrolyte membrane between a pair of catalyst layers, in which the catalyst layer comprises a polymer electrolyte and particles carrying a catalyst material, and in which the volume of fine pores having a diameter of 1.0 μm or smaller is increased toward the polymer electrolyte membrane from the surface of the catalyst layer.