A fuel cell having a structure capable of certainly supplying a gas by making effective use of a limited space while ensuring the portability of the fuel cell is provided. The fuel cell includes two generators, a fuel supply portion, and two planar current collectors. Each of the generators has a proton conductor film, and a planar hydrogen side electrode and a planar oxygen side electrode disposed with the proton conductor film held therebetween. The fuel supply portion is adapted to supply a fuel to the hydrogen side electrodes of the generators. The planar current collectors, which are disposed in close-contact with the oxygen side electrodes of the generators, have gas transmission portions such as opening portions allowing the oxygen side electrodes to be opened to atmosphere. Since the oxygen side electrodes are opened to atmosphere, oxygen can be supplied to the generators without lowering a partial pressure of oxygen in air.