A fuel cell system includes a water supply unit configured to supply water from a first water storage unit to a second water storage unit, and a water usage unit uses water in the second water storage unit. The first and second water storage units store produced water form the fuel cell. When the amount of water stored in the first water storage unit exceeds a first predetermined value and the amount of water stored in the second water storage unit is smaller than a second predetermined value, water is supplied from the first water storage unit to the second water storage unit. When water is being used by the water usage unit, water is supplied from the first water storage unit to the second water storage unit even when the amount of water stored in the second water storage unit is not smaller than the second predetermined value.