A fuel cell which can self-heat in a short time, in which no reaction gas is necessary for combustion, thereby improving the starting performance at low temperatures. The fuel cell comprises a cell structure in which an anode and a cathode are provided on either side of a solid polymer electrolyte membrane. This cell structure has a power generation plane and at least a part of the generation plane is defined as a local generation area so as to locally generate power. The fuel cell may include a pair of separators between which the cell structure is placed, and a reaction gas passage may be formed between the cell structure and each separator. One of a system for supplying a reaction gas to only a part of the reaction gas passage, and a system for supplying a reaction gas to the entire reaction gas passage is switchably selected.