Abstract: A method of manufacturing a stainless pipe is provided. The method includes gradually curving the stainless pipe into a ring type, plasma-welding opposite ends of the curved stainless pipe so that back beads are formed, additionally TIG-welding the plasma-welded part to form bead mountings, externally applying pressure force onto an outer portion of the stainless pipe while inserting a mandrel into the welded stainless pipe such that the mandrel comes into contact with the back beads, thereby flattening the back beads, removing the bead mountains, setting an outer diameter of the stainless pipe, RF heat-treating the welded part, cooling the welded part, and a second sizing stage.