PURPOSE: To prevent an outer pipe from buckling and cracking by providing a support member to axially support one end of an inner pipe part on a draw/ bend die and pressing the other end of the inner pipe part through a pressing die.

CONSTITUTION: The outer pipe 4b of the double pipe 4 is clamped by a clamp die 2 and the draw/bend die 1 and bent by rotating the bending die 1 in the direction of an arrow mark(chevron) as it is restrained by a pressure die 3. The front end of the inner pipe 4a is supported by a jig 13 and the rear end is supported by a pressing die 5 as it is acted by pressure and bent as a pressing vector is acted in the direction of an arrow (b). A suitable bending moment (a) is acted by the behavior of the jig 13 generated by rotation of the draw/bend die 1 on the inner pipe 4a and the inner pipe is pushed and bent smoothly. A core bar 7 into which a heater 8 is interpolated is inserted into the inner pipe 4a and the inner pipe is pressed and bent more smoothly by the thermal operation of the heater without being flattened.