PURPOSE: To mold a synthetic resin pipe having a uniform thickness and is superior in watertightness by a method wherein two strips of sheet are heated at a specific temperature by interposing a plurality of strips of tapes in between, a tubular body is formed by winding them spirally around an imaginary cylindrical rotating shaft body, fused through press contacting with a press roll and cured through cooling.

CONSTITUTION: Two strips of sheet B comprised of low-density polyethylene forming a surface layer and four sheets of strips of tape C comprised of a laminated sheet of high-density and low-density polyethylene sheets, which form an interlayer and having a width of half as wide as that of the strip of sheet B or narrower, are heated at the softening point or higher and the melting point or lower of them by passing them through a hot air heating sphere D. Positions of both side parts of four sheets of strips of tape C each are slid in the crosswise direction and wound spirally round an imaginary cylindrical rotating shaft body A by interposing between the strips of sheet B. At the time of this winding the tape C wound up previously and the tape C wound up afterward form a tubular body (a) so that they juxtapose each other, fused through press contacting with a facing and contacting press roll E and cured through cooling.