A method of producing a reinforcing fiber preform includes: holding at least one substrate laminate by a shaping mold composed of at least two molds that face each other, wherein the at least one substrate laminate is selected from a substrate laminate produced by laminating multiple reinforcing fiber substrates each having a fixing material applied to at least one surface thereof and a substrate laminate produced by laminating multiple reinforcing fiber substrates with the fixing material interposed therebetween; and subsequently applying an electric current to the substrate laminate in a direction of lamination to heat the reinforcing fiber substrates and thereby apply heat to the fixing material to fix substrate layers in the substrate laminate to each other; wherein a means of making electric resistance in a fixing area is relatively lower compared to that in a non-fixing area in the substrate laminate.