FUEL CELL

A fuel cell comprises a membrane electrode assembly, gas diffusion layers in a pair provided in such a manner that the membrane electrode assembly is interposed therebetween, and separators in a pair provided in such a manner that the gas diffusion layers in a pair are interposed therebetween. At least one of the separators in a pair has on a surface facing the gas diffusion layer a flow path part causing a reaction gas to flow therein, and a rib part provided next to the flow path part and in contact with the gas diffusion layer. The flow path part has a bottom surface spaced apart from the gas diffusion layer, and a side portion connecting the bottom surface and the rib part to each other. The side portion is provided with a groove extending from a connection between the side portion and the rib part toward the bottom surface.