FUEL CELL SYSTEM

A fuel cell system, provided with: a fuel-generating material which generates a fuel by a chemical reaction and which can be regenerated by a reverse reaction of the aforementioned chemical reaction; a first fuel cell in which gas is circulated with respect to the fuel-generating material; and a second fuel cell for generating power using a fuel gas introduced from an external gas supply source. The amount of heat generated in the second fuel cell performing a power generation operation is transmitted to the first fuel cell preforming an electrolysis operation.