To increase the number of projections per one lead of a thread and further enhance a locking effect in a method of manufacturing a male screw provided with the projections which project in the normal direction of a flank of the thread at appropriate places of the thread.

At least one of a plurality of rolling dies 12, 13 includes a plurality of dropped parts 17, 18, 23, 24 within a range of one last rotation of a material 1' of terminal end portions of die faces 14, 20. When the material 1' passes the dropped parts 17, 18, 23, 24, edge parts formed between falling parts 17a, 18a, 23a, 24a of the dropped parts 17, 18, 23, 24 and projecting strips of die faces 14, 20 corresponding to screw grooves of a finished male screw bite into the material 1', and the corresponding portions of the material 1' are pushed outward, and thereby, a plurality of the projections are formed per one lead of the thread.