Provided is a fuel system comprising a fuel vessel, molded parts for the fuel vessel and/or a tube for a fuel in which bodies are constituted from a thermoplastic resin and/or a rubber, wherein a coating layer is formed on the surfaces in at least one sides of the insides and the outsides of the fuel vessel body, the molded part bodies for the fuel vessel and/or the tube body for a fuel or at least one of connected parts with these bodies; the above coating layer is formed by curing an epoxy resin composition comprising an epoxy resin and an epoxy resin curing agent as principal components; and the above coating layer has a gasoline permeability coefficient of 2 g·mm/m2·day or less at 23° C. and a relative humidity of 60% RH. The above coating layer is excellent in a permeation-preventing performance against an automobile fuel (gasoline barrier property), a heat resistance and an impact resistance, then a fuel vessel, molded parts for the fuel vessel and a tube which have excellent performances are obtained.