Fuel cell system

Disclosed is a fuel cell system including: a fuel cell including an anode to which fuel is supplied, and a cathode to which oxidant is supplied; an operation controlling unit for controlling operation of the fuel cell; an oxygen consumption amount detection means for detecting an amount of oxygen consumed in the fuel cell; and at least one of a first alarm means and a first stop commanding means, the first alarm means being configured to output an alarm when the amount of oxygen consumed is equal to or greater than a first reference value, and the first stop commanding means being configured to issue a stop command for stopping power generation by the fuel cell to the operation controlling unit when the amount of oxygen consumed is equal to or greater than a second reference value.