A fuel cell system comprises a fuel cell, a fuel gas passage through which a fuel gas containing an odorant and hydrogen gas supplied to the fuel cell flows, an oxidative gas passage through which an oxidative gas supplied to the fuel cell flows, a fuel off gas passage through which a fuel off gas discharged from the fuel cell flows, an oxidative off gas passage through which an oxidative off gas discharged from the fuel cell flows, and an odorant removal portion provided in the fuel off gas passage. The odorant removal portion removes the odorant after the fuel gas has been introduced into the fuel cell.