To provide a manufacturing method of a pair tube with superior heat insulation by using an automatic machine, and to provide a conduit material for floor heating providing easy insertion of the pair tube into a CD tube.

The manufacturing method of the conduit material for hot water type floor heating is comprised of a process of extruding two resin made tubes 2, 3 in parallel with each other from an extruder at the same time, a process of covering exteriors of the two tubes 2, 3 by a heat insulating material 5 to embrace the tubes, a process of forming one pair tube 4 by spirally winding aluminum made tape 6 around the exteriors of the tubes 2, 3 covered by the heat insulating material 5 and bundling the two tubes 2, 3, and a process of inserting the pair tube 4 into the elliptical CD tube 9. The conduit is manufactured by the processes.