A fuel cell that can prevent local accumulation of a reaction-irrelevant gas in the fuel cell. A gas diffusion layer is stacked on a membrane electrode assembly, which is a stack of an electrolyte membrane and electrode catalyst layers. A separator including gas flow channels is attached to the gas diffusion layer such that the gas flow channels are adjacent to the gas diffusion layer. A gas distribution channel through which gas supplied to the membrane electrode assembly flows is formed in the separator. The gas flow channels communicate with the gas distribution channel at upstream ends thereof and are substantially closed at downstream ends thereof. The gas flow channels are configured so that downstream parts of the gas flow channels and upstream parts of the gas flow channels are adjacent to each other.