FUEL CELL SYSTEM AND CONTROL METHOD OF FUEL CELL SYSTEM

A fuel cell system includes a fuel cell, an oxidant gas supply and discharge system, a coolant circulation system, a compressor, an atmospheric pressure sensor, and a control unit. When a measured atmospheric pressure becomes lower than a predetermined reference atmospheric pressure, the control unit executes temperature and pressure lowering control for controlling the coolant circulation system to lower the temperature of the fuel cell while controlling a pressure-regulating valve to lower a delivery pressure of the compressor.