To provide a method for joining fixed tubes by means of easily workable edge preparation in place of a single U groove that is difficult to machine and likely to cause weld defects.

The method is to join a circumferential joint between unrevolving tubes by an automatic welding method. The method is such that edge preparation is performed on the outside of both tube ends to be joined so as to prepare a single V groove with a V-angle of 90° or more, and that both tube ends to be joined are fixed with the ends abuting on each other. Then, with a hot wire type TIG automatic welding machine travelling along the single V groove of the abutting part in the circumferential direction of the tube, and with the V groove being filled, both fixed tubes are joined by welding.