To provide a raw material for a worm and a method for manufacturing the worm which does not cause any underfill groove on the tip of the edge area of a screw tooth in forming the screw tooth on the raw material for the worm by equalizing the push-in resistance of the raw material against a roll die at a position in the circumferential direction of a screw tooth forming section.

Curved recesses 5 and 5 which are concavely curved to both sides in the circumferential direction are provided on both ends of the screw tooth forming section 1 where single-thread or multi-thread screw tooth is formed by form rolling, with the position of the edge of the screw tooth as the deepest point a. Both ends in the circumferential direction of the adjoining curved recesses 5 and 5 are designed to join on curved projections 5c and 5c which are curved projectingly.