PURPOSE: To eliminate possibility of separation of a resin layer from a metal tub so as to be stably usable for a long period by securing a resin layer to a metal tube at a faucet with an expanded diameter.

CONSTITUTION: A composite tube 10 has a faucet 10a at one end part of the tube. The faucet 10a is concentrically diameter-expanded to a tube main body part 10b except the faucet 10a, consequently a metal tube 11 and a synthetic resin layer 12 at the faucet 10a are also in a concentrically diameter-expand condition to the metal tube 11 and he synthetic resin layer 12 of the main body part 10b. Many through holes 11a, 11a... are provided at suitable intervals in the periphery and axial directions in the metal tube 11 part in the diameter- expanded condition in the faucet 10a. In this case, a part of a synthetic resin composing the synthetic resin layer 12 is protruded to the outside of the metal tube 11 through each hole 11a, and the protruded part is made larger in diameter than each through hole 11a to be secured on the outer peripheral surface of the metal tube 11.