A fuel cell system is equipped with a control unit that controls a rotational speed of the turbo compressor that supplies air to an air supply flow passage and an opening degree of at least one valve that adjusts a flow rate and a pressure of the air supplied to a fuel cell such that an operating point of the turbo compressor becomes a target operating point. The control unit sets the target operating point within an operating point range that is on the higher flow rate side than at least part of a first region where an amount of change in flow rate is larger than a predetermined value when a pressure ratio of the turbo compressor is changed by a predetermined amount at a same rotational speed, on a higher flow rate side than a surging region, when a predetermined condition is fulfilled.