An electrical wire routing device for routing an electric wire between a floor in an automobile and a seat includes a case following parallel to a support rail to which a support body supporting the seat is slidably attached. The case includes a tubelar movement section attaching the electric wire thereto, guiding the electric wire to the seat, to which a slider sliding in association with the movement of the seat is slidably attached, and a housing section accommodating the extra length of the electric wire. The movement section and the housing section are provided as separated parts and placed parallel to each other. The extra length of the electric wire extracted from one end portion of the movement section and drawn into the housing section is accommodated in the housing section with the electric wire bent in a U-shape. The electric wire is accommodated in the corrugated tube.