FUEL CELL SYSTEM AND WATER CONTENT CONTROL METHOD OF FUEL CELL

A fuel cell system configured to control a water content of a fuel cell includes: a fuel cell including an electrolyte membrane, an anode formed on one surface of the electrolyte membrane, and a cathode formed on the other surface of the electrolyte membrane; an estimation portion configured to estimate a water content existing in an anode side; and a controlling portion configured such that, when the water content in the anode side, estimated by the estimation portion, is a threshold or more, the controlling portion maintains, at a predetermined rate, a flow rate of an anode gas flowing in the anode side, and controls a flow rate of a cathode gas flowing in a cathode side to be less than a predetermined rate. The estimation of the water content may be based on a voltage fluctuation of the fuel cell.