FUEL CELL SYSTEM

A fuel cell system includes a supply valve for supplying an anode gas into an anode system, a purge valve for discharging an off-gas from the anode system, a pressure detecting portion configured to estimate or measures a pressure inside the anode system, a supply valve control portion configured to control an open/close operation of the supply valve based on a load of the fuel cell, a purge flow rate estimating portion configured to estimate a purge flow rate of the off-gas discharged from the anode system through the purge valve based on a pressure decrease inside the anode system in a supply valve close state, and a purge valve control portion configured to open the purge valve in synchronization with the supply valve close state.