FUEL CELL SYSTEM

A fuel cell system includes: a reaction gas supply unit configured to supply a reaction gas to a fuel cell stack; a humidifier configured to transfer moisture from an off-gas discharged from the fuel cell stack to the reaction gas; and a controller configured to control the reaction gas supply unit so as to regulate a supply amount of the reaction gas, wherein the controller is configured to acquire a temperature of the humidifier and set the supply amount of the reaction gas based on a target power generation amount of the fuel cell stack, and in a case where the temperature of the humidifier is equal to or lower than a prescribed warm-up determination value, the controller executes warm-up control to increase the supply amount of the reaction gas as compared with a case where the temperature of the humidifier is higher than the warm-up determination value.