PURPOSE: To obtain a metallic pipe having a smooth inside surface by forming a metallic tape into a pipe in such a manner that the seam thereof faces a three o'clock position and welding the seam.

CONSTITUTION: The tape 2' consisting of Al, etc. faces perpendicular and is successively formed into a pipe in such a manner that the seam 2A' thereof faces the three o'clock position. The formed tape 2' is held retained by a press roll so as not to open the seam 2A' and is successively welded in this state. Since the seam 2A' is welded in the three o'clock position, the adverse influence of gravity to the weld zone 2A is eliminated and the projection of the weld zone 2A into the metallic pipe 2 is suppressed. The metallic pipe 2 having the smooth bore surface is thus easily obtd.