Abstract: A method and apparatus for doubling and twisting a material yarn by a two-step changeover system by utilizing a pot twisting and winding device is disclosed. To produce a doubled and twisted yarn having a yarn configuration of two component yarns forming the yarn in a balanced condition, when the second step operation is carried out so as to double a primary twisted yarn of a yarn package formed in the pot by a first step operation with a yarn fed from a supply source and twist this doubled yarn while eliminating the primary twists imparted to the material yarn, the position of the bottom end of the traverse tube in the pot must be controlled so as to satisfy a particular condition D.sub.2 .gtoreq. L.sub.2, where D.sub.2 represents an inside diameter of the full size yarn package formed in the pot by the first step operation, while L.sub.2 represents a distance between the bottom end of the traverse tube and an inside bottom surface of the pot.