Fuel cell system

A fuel cell system includes a fuel cell stack; a fuel gas supply pipe supplying a fuel gas to the fuel cell stack; an injector injecting the fuel gas supplied from the fuel gas supply pipe into the fuel cell stack through a piping unit; and a buffer part located at an upstream side of the injector and being capable of circulating the fuel gas. The buffer part includes: a manifold; and a buffer tank connected to the manifold and circulating the fuel gas, and the manifold is disposed between the fuel gas supply pipe and the piping unit.