FUEL CELL APPARATUS

A fuel cell system includes a controller (30) that controls an amount of air flow to be supplied from an air blower (B1) included in an oxygen-containing gas supply (13) to a cell stack (11) to cause a power level (in amperes) of a fuel cell controllable by a power level regulator (power conditioner 20) and an air utilization (Ua) to have an increase-control section in which the air utilization (Ua) increases in accordance with an increase in the power level of the fuel cell and a decrease-control section in which the air utilization (Ua) decreases in accordance with an increase in the power level. The air utilization (Ua) is a ratio of an air amount used by the fuel cell for power generation to an oxygen-containing gas (air) amount supplied to the fuel cell.