PURPOSE: To economically obtain a composite tube consisting of an intermediate sand-contained resin layer with clean internal/external surfaces by forming an external reinforcing resin layer of a faucet part as far as part of a barrel forming surface and forming a barrel sand-contained resin layer under such condition that part of the sand layer remains untouched.

CONSTITUTION: An external reinforcing resin layer A of a faucet part is formed across a faucet forming surface 2a, a step-forming surface 2b and part of a barrel forming surface 2c. On the said layer A, the sand-contained resin layer B of the faucet is formed by sequentially supplying a resin solution and sand to regions corresponding to the forming surfaces 2a, 2b. Then on the layer B, a reinforcing resin layer C of a faucet part is formed. Following this process, a prearranged amount of insertion of an internal surface restraining tool 8 for the faucet is provided, so that it is connected to the layer C. Thus an external barrel reinforcing layer D is formed on the forming surface 2C. Further, on the layer D, a barrel sand-contained resin layer F is formed under such condition that part of the sand layer E remains untouched by sequentially supplying a resin solution and sand. Finally on the layer F, an internal barrel reinforcing layer G is formed and along with this process, a resin solution is impregnated into the layer E. In this manner, it is possible to provide the external peripheral surface of the barrel part where sand is not exposed and easily and surely level off the sand layer E.