Fuel cell

The present invention is to provide an efficient cooling by supplying air and cooling water simultaneously while keeping cooling and wetting of a membrane without having a fuel cell large-sized. A fuel cell includes a separator 10B between unit cells 10A adjacent to each other. The separator includes an air pass S1 on a front surface side abutting at least on a cathode of the unit cell and it includes a cooling space S2 supplied with air and water on the rear side thereof to cool the unit cell with latent heat of water evaporated by heat of the unit cell transmitted to the cooling space. Thereby, the unit cell is cooled via the separator and clogging up of the air pass caused by water entering is prevented.