A fuel cell system includes: a fuel cell that causes electrochemical reaction of an anode gas and a cathode gas; a plurality of auxiliary machines that are used for operation of the fuel cell; and a fuel cell system case that is configured to place the fuel cell and the plurality of auxiliary machines therein, wherein, in the fuel cell system case, a surface from which a first cable harness including first electric wire used for supplying electric power to the plurality of auxiliary machines is taken out differs from a surface from which a second cable harness including second electric wire for supplying larger electric power than the electric power of the first electric wire is taken out.