To provide a method for manufacturing a hourglass worm gear for improving mass-productivity as a whole by making a hourglass worm combined with a gear excellent in mass-productivity by using the gear it is as a worm wheel, in consideration of conventional technical problems and actual conditions.

An electrodeposited grinding wheel is made by electro-depositing abrasive grain on a tooth flank of a base gear having substantially the same tooth shape as that of the gear used as the worm wheel. By mounting the electrodeposited grinding wheel and the worm material on a work axis and a hob shaft of a hob machine, respectively, the hourglass worm is made. The worm and the gear are combined.