An object of the present invention is to provide a membrane-electrode-frame assembly which suppresses reductions in power generation properties due to gas cross leakage of a polymer electrolyte fuel cell, which improves durability of a polymer electrolyte membrane and which exhibits superior productivity. In the membrane-electrode-frame assembly, an unwoven fabric which has two domains each having different pore sizes and which is formed with fibers of PVDF is disposed as a reinforcing membrane in a polymer electrolyte membrane for a polymer electrolyte fuel cell, and a domain having a smaller pore size and protruding from the polymer electrolyte membrane and a frame are formed into an integrated structure by welding, thereby improving a gas sealing capability.