Abstract: A fuel cell system installed in a vehicle includes: a fuel cell; a secondary battery; a load including a drive motor and an air compressor; a fuel cell converter; a secondary battery converter; a failure detection unit; a first state determination unit; a reverse rotation detection unit; and a control unit. The control unit performs a limp-home traveling control that supplies electric power from the secondary battery to the drive motor when the secondary battery converter fails. When the vehicle is not in the first state, the control unit prohibits regeneration of the drive motor. When the vehicle is in the first state, the control unit supplies a reaction current to the air compressor. When the reaction current is applied and a reverse rotation of the air compressor is detected, the control unit does not apply the reaction current thereafter.