Fuel Cell System and Method of Controlling the Same

A fuel cell system and a method of controlling the same are disclosed. The fuel cell system includes a hydrogen pressure adjuster configured to adjust a hydrogen supply pressure of hydrogen supplied to a fuel cell stack, and a controller configured to determine whether or not a control mode for controlling the hydrogen supply pressure is required, based on a state of the fuel cell stack, and to control the hydrogen pressure adjuster to vary the hydrogen supply pressure in a predetermined pressure range based on a pressure increase rate or a pressure decrease rate, when the control mode is required.