A single cell C includes a membrane electrode assembly M in which an electrolyte membrane 1 is interposed between a pair of electrode layers 2, 3, and a pair of separators 4 that form gas channels C between the pair of separators 4 and the membrane electrode assembly M, wherein the electrode layers 2, 3 include first gas diffusion layers 2B, 3B of a porous material disposed at the side facing the electrolyte membrane 1 and second gas diffusion layers 2C, 3C that are composed of a metal porous body having arrayed many holes K, and a part of the first gas diffusion layers 2B, 3B penetrates the holes K of the second gas diffusion layers 2C, 3C to form protrusions T. Accordingly, the surface of the electrode layers 2, 3 has a fine uneven structure. As a result, an improvement in liquid water discharging function and an improvement in power generating function were achieved at the same time.