FUEL CELL SYSTEM

A fuel cell system may include: a fuel cell; a hydrogen gas supply passage; a solenoid valve that changes an opening degree of the hydrogen gas supply passage; a pressure sensor that detects a pressure in a downstream supply passage being a part of the hydrogen gas supply passage from the solenoid valve to the fuel cell; and a control circuit. The control circuit detects a rise in the pressure detected by the pressure sensor when increasing a conducted electric current conducted in the solenoid valve from a state where the solenoid valve is closed, and detection of a rising current which is the conducted electric current at a time of the rise in the pressure; and calculates an increase characteristic based on the rising current, the increase characteristic being a relationship between the conducted electric current and the pressure when the conducted electric current increases.