PURPOSE: To mold the receiving port of a composite pipe not generating possibility such that a synthetic resin layer is released from the inner peripheral surface of a metal pipe by providing elastic force not breaking an adhesive layer at the time of diametric expansion to the adhesive layer and expanding the diameter of the synthetic resin layer in the quantity corresponding to the diametrically reduced quantity of the adhesive layer by the diameter reducing force remaining in the adhesive layer by diametric expansion.

CONSTITUTION: In a cold state, diameter expanding force is internally applied to the end part of a composite pipe 10 whose receiving port must be molded to expand the diameter of the metal pipe 11 and synthetic resin layer 13 at the end part of the composite pipe 10. At this time, since the adhesive layer 12 interposed between the metal pipe 11 and the synthetic resin layer 13 can be elastically deformed, the adhesive layer 12 is pressed to the inner peripheral surface of the metal pipe 11 by the diametric expansion of the synthetic resin layer 13 to be compressed in the diametric direction and stretched in the peripheral direction. When the diameter expanding force is removed from the end part of the composite pipe 10, the metal pipe 11 at the end part is reduced in its diameter by spring back and the synthetic resin layer 13 is reduced in its diameter by this diameter reducing force and the adhesive layer 12 becomes an expanded state from the state compressed in the diameter direction by the diameter reducing force of the synthetic resin layer 13. By this method, there is no possibility such that the bonding surface of the metal pipe 11 and the adhesive layer 12 and the bonding surface of the adhesive layer 12 and the synthetic resin layer 13 are released.