PURPOSE: To form a uniform and thick resin layer melt-stuck on the inner surface of a pipe by alternately repeating both the flow of resin powder and the flow of hot air through the pipe.

CONSTITUTION: A melt-stuck resin layer is formed on the inner surface of a metallic pipe 1 by allowing resin powder 12 stored in a storage tank 4 to flow together with air through the pipe 1 while rotating the preheated metallic pipe 1 to the circumferential direction. Then the surface layer part of the melt-stuck resin layer is melted by passing hot air through the pipe 1 via a hot air blower 9 and a pipe 10. Successively the melt-stuck resin layer is formed on the above- mentioned melted resin face by allowing resin powder to reflow together with air. The thick melt-stuck resin layer is formed on the inner surface of the pipe by alternately repeating both the flow of resin powder and the flow of hot air through the pipe. As a result, the coated resin layer is formed which is free from thermal deterioration of an adhesive layer between the metallic pipe and the melt-stuck resin layer, excellent in adhesive force, uniform and thick.