FUEL CELL SYSTEM

A fuel cell system includes: a reformer (2) which generates a reformed gas (F05) containing hydrogen by reacting hydrocarbon and moisture with each other; a fuel cell stack (1) which generates electric energy through electrochemical reaction of the reformed gas (F05) and an oxidant (F03); an ejector which, using steam (F11) as a drive fluid, sucks either a raw fuel (F01) containing the hydrocarbon or a recycled gas (F07) recovered from an anode exhaust gas (F06), and supplies a resultant gas to the reformer (2); and a vaporizer (4) which generates the steam (F11) by vaporizing water, wherein an operation temperature of the fuel cell stack (1) is higher than a boiling point of water at an operation pressure, and the vaporizer (4) generates the steam (F11) through heat exchange with the anode exhaust gas (F06).