An object of the present invention is to provide a fuel system part with excellent fuel permeation resistance, and excellent shock impact resistance and heat resistance. A fuel system part consists of a resin composition, wherein the resin composition includes (a) a polyphenylene sulfide resin and (b) an olefin based resin, wherein an amount of the (a) polyphenylene sulfide resin and the (b) olefin based resin is 80 weight % or more of the entire resin composition and the content of the (b) olefin based resin is 10 to 100 parts by weight relevant to 100 parts by weight of the (a) polyphenylene sulfide resin, and wherein the resin composition has a fuel permeability coefficient (Fuel C/ethanol = 90/10) of 3.3 x 10<-16> mol . m/m<2> . s . Pa or less at 40 DEG C.
