To enhance the production efficiency by producing a large size quartz glass tube comprising a plurality of straight tubular parts having different shapes without welding the straight tubular parts, and to obtain a unified, large size quartz glass tube free from connection points and having various structures.

The integrally formed quartz glass tube free from connection points and having various structures is obtained by attaching a quartz glass tube 1 to a glass lathe, then increasing the diameter of the glass tube 1 by blowing up the quartz glass tube by a burner 3 while rotating it, narrowing down the quartz glass tube having an enlarged diameter into a diameter smaller than the initial diameter by heating the quartz glass tube by a burner while applying a carbon jig, forming the R-part 13 by pressing a jig having the R-shape to the narrowed down part 12, and forming a tapered part 14 by performing running-in working by using a burner while pressing a stepped structural carbon roller having a taper part.