FUEL CELL SYSTEM

A fuel cell system (1) includes: a fuel cell (51); an evaporating unit (32) producing water vapor from reforming water; a reforming unit (33) producing reforming gas from a reforming raw material and the water vapor and supplying the reforming gas to the fuel cell; a combustion unit (35) burning combustible gas from a combustion electrode of the fuel cell and heating the evaporating unit and the reforming unit; a heating device (35c, 35d) igniting the combustible gas by heating the combustible gas and firing up the combustion unit; a first temperature sensor (37) in the combustion unit; a second temperature sensor (38) in the inside of at least one of the evaporating unit and the reforming unit ; and a control device (15) controlling the fuel cell. The claimed fuel cell system is able to determine reliably during start-up wether the combustion unit (35) has reached a state a combustion state where a flame is continuous.