PURPOSE: To easily manufacture the spiral bar stock made to the spiral shape by heating a deformed bar stock locally, applying the twisting force on this part, moving this heated part to the axial direction and subjecting it continuously to hot twisting.

CONSTITUTION: One end of the deformed section bar stock 2 is fixed with the bar holding tool 5, and the other end is set to the chuck 7. The induction heating coil 10 is positioned to one end of the part of bar stock to be formed in the spiral shape, the heating for the bar stock is started by energizing the coil and also this induction heating coil is moved to the left hand along the bar stock with the coil moving device 12. At the same time, one end of bar stock is twisted and turned with the twisting device 6. The heated part of the bar stock is twisted and deformed, by moving the position to be heated in the axial direction of the bar stock, the bar stock of the prescribed area is hot-worked plastically and the spiral part 1a is formed. Therefore, the spiral shaped part can be formed only on the required part of the bar stock, and the spiral bar stock of many kinds of the design can be manufactured by changing the pitch of the spiral arbitrarily.