Brennstoffzellensystem

This fuel cell system is for suppressing a backflow of water from an exhaust pipe outlet that discharges a reactant-off gas, without decreasing the performance and fuel consumption of a fuel cell, the exhaust pipe being configured to switch between a main discharge pipe and a sub discharge pipe by a switching means to discharge the reactant-off gas. The sub discharge pipe includes a rising gradient portion formed to incline upwards above a gradient of the main discharge pipe and a falling gradient portion formed to incline downwards at the downstream of the rising gradient portion. The switching valve switches to allow the reactant-off gas to be discharged from the main discharge pipe if an amount of reactant-off gas to be discharged is equal to or above a threshold value of an amount of discharge, and allow the reactant-off gas to be discharged from the sub discharge pipe if the amount of reactant-off gas to be discharged is below the threshold value of the amount of discharge.