An object of the invention is to provide an electrode catalyst layer of a solid polymer electrolyte membrane-electrode assembly expressing excellent balance between water retention and drainage in an electrode, good power generation performance under any of low humidity and high humidity conditions, and also excellent durability of power generation.The electrode catalyst layer of the invention contains catalyst particles, an ion exchange resin and a water repellent agent, wherein said water repellent agent contains at least one kind selected from the group consisting of (A) a fluorine-containing copolymer having a structure unit derived from a polyfluoroalkyl-containing (meth)acrylate and (B) a fluorine-containing copolymer having a specific structure unit derived from a fluorine-containing olefin monomer and a specific structure unit derived from a vinyl ether monomer.