The power controller starts imposing the current limit when a condition for the current limit is met the condition, the condition being that the fuel cell does not generate to fulfill the requested amount of power generation while the fuel cell generates power at an upper limit of the supply capability of the fuel gas supply unit, and the power controller removes the current limit at a first predetermined increase rate determined when the requested amount of power generation exceeds a predetermined threshold below a rated power generation amount of the fuel cell and at a second increase rate higher than the first increase rate when the requested amount of power generation is the threshold or less, after the condition for the limit is dissolved.