A gas diffusion layer (6) is sandwiched between catalyst electrode layers (5) and separators (1, 2), and side faces (6A, 6B) of the gas diffusion layer (6) are arranged so as to face a gas inlet manifold (7) and outlet manifold (8), and partition the inlet manifold (7) and outlet manifold (8). In the gas diffusion layer (6), gas flows from the side face (6A) facing the inlet manifold (7), flows through the interior, and flows out from the side face (6B) facing the outlet manifold (8).