PURPOSE: To work thoroughly screw threads just before a step part by mounting circular dies with the chamfer and flank positioned reverse from an ordinary case, inserting loosely the work which has the step part and with which through- rolling is infeasible into the space between the dies just before the step part before working thereof, subjecting the work to rolling and allowing the work to walk backward.

CONSTITUTION: Each die 1 is disposed in order of a flank 4, a forming part 3 and a chamfer 2, reverse from an ordinary case. Thereupon, the part to be worked with screw threads of a work piece P which has a step part P1 and with which through-rolling is infeasible is inserted freely into the space between the dies 1 just before the part P1. The safe distance S between the end face of the part P1 and the end face of the dies 1 can be made much smaller than the distance in the prior art. If the work piece P is subjected to prescribed rolling in this stage, the work piece is walking-rolled in the direction reverse from the insertion direction and is returned out backward, whereby the rolling is completed. The length E' of the imperfect thread part is thus decreased considerably.