A fuel cell system (1) capable of securely removing moisture in particulate form floating in an exhaust gas passage along with impurities mixed in the moisture, enhancing the performance of a fuel cell, and extending the service life of the fuel cell. The fuel cell system (1) includes a gas circulation system for recirculating and resupplying an exhaust gas to a fuel cell (100). This gas circulation system is equipped with an ion exchange resin member (20) that adsorbs impurity components contained in the moisture particles mixed in the exhaust gas flowing through the gas circulation system. The gas circulation system resupplies fluid that has passed through the ion exchange resin member (20) to the fuel cell (100).