A fuel cell includes cell units each composed of a hydrogen ion conductive polymeric electrolyte membrane, a pair of electrodes arranged on the front and rear faces of the hydrogen ion conductive polymeric electrolyte membrane, and a diffusion layer contacting the electrodes to cover the electrodes. The cell units are pushed down by an end plate having a current-collecting metallic plate and a resin substrate for fixing the current-collecting metallic plate. A layer having a humidity-adjusting component is formed on the surface of the resin substrate of the end plate.