FUEL CELL SYSTEM AND OPERATION METHOD THEREOF

PROBLEM TO BE SOLVED: To ensure that, even when the amount of power generated by a fuel cell stack changes jumping over a power generation inhibited region, the user may not feel a sense of discomfort.SOLUTION: An operation method of a fuel cell system 1 having a fuel cell stack 2 which generates electric power using fuel gas supplied to an anode and oxidant gas supplied to a cathode is such that when in a prescribed power generation inhibited region, no power is generated, while, when in other than the power generation inhibited region, oxidant gas is supplied to the fuel cell stack 2 corresponding to a requested power generation amount, and, when the fuel cell stack 2 changes a power generation amount jumping over the power generation inhibited region, the amount of oxidant gas supplied is not corresponded to a requested power generation amount and a change rate of the amount of oxidant gas supplied is, as a permissible change rate, gradually incremented or gradually decremented, in which way the amount of oxidant gas supplied is brought closer to the one which corresponds to a power generation amount jumping over the power generation inhibited region.