FUEL CELL SYSTEM AND CONTROL METHOD THEREOF

Provided is a fuel cell system including: a pressure measurement unit that acquires a measured pressure value of an anode gas at an anode gas inlet or an anode gas outlet of a fuel cell; and a water amount estimation unit. The water amount estimation unit obtains, from a plurality of circumstantial parameters including an open time of an injector provided in the anode gas supply passage and the measured pressure value measured before the injector is opened, an assumed pressure rise that is assumed based on the water amount being equal to the water amount threshold value. When a measured pressure rise of the measured pressure value resulting from opening the injector is larger than the assumed pressure rise, the water amount estimation unit estimates that the water amount is larger than the water amount threshold value.