FUEL CELL SYSTEM

A fuel cell system may include: a stack for generating power through an electrochemical reaction of reforming gas and air; a fuel processing apparatus for generating the reforming gas supplied to the stack; a water supply tank for storing the water; a heat recovery tank for storing hot water; a first heat exchanger disposed in the fuel processing apparatus, and exchanging heat between cooling water and exhaust gas discharged from the fuel processing apparatus; and a heat supply valve for supplying the cooling water to the water supply tank or the heat recovery tank so as to heat the water stored in the water supply tank or the hot water stored in the heat recovery tank.