Abstract: An undercover for a vehicle, which covers a silencer which is disposed on a lower surface of a body of the vehicle for discharging reacted gas of a fuel-cell mounted in the vehicle, wherein an opening is formed so as to correspond in position to an open portion which is formed at an end of a discharge pipe of the silencer.

Abstract: An undercover for a vehicle, which covers a silencer which is disposed on a lower surface of a body of the vehicle for discharging reacted gas of a fuel-cell mounted in the vehicle, wherein an opening is formed so as to correspond in position to an open portion which is formed at an end of a discharge pipe of the silencer.

Abstract: This fuel cell system is provided with: a fuel cell which is supplied with cathode gas and anode gas and generates electrical power; a discharged gas processing device which mixes and dilutes cathode off-gas and anode off-gas discharged from the fuel cell; a discharge gas pipe through which exhaust gas discharged from the discharged gas processing device flows; a specific gas concentration sensor disposed in the discharge gas pipe, which measures a concentration of a specific gas in the exhaust gas; and an enlarged cross-section area flow path section provided between the discharged gas processing device and the specific gas concentration sensor, and having a flow path cross-section area that is larger than that of the discharge gas pipe.