Abstract: Disclosed herein are a helical gear forging apparatus wherein a forming introduction portion thereof, used to form gear teeth of the helical gear, is variable in shape on the basis of the desired helix angle of the gear-teeth so as to constantly keep a predetermined outer diameter of the formed gear teeth, thereby enabling easy forming of the helical gear irrespective of a variation of the helix angle, and a forging method using the same. The forging apparatus comprises a gear die having a gear teeth forming section defined at an inner circumference thereof for forming gear teeth of the helical gear, a collar die integrally formed at an upper end of the gear die, a lower die located below the gear die, a punch located above the collar die and adapted to push a stock into the collar die, and a knock-out located below the lower die and adapted to discharge the molded stock to the outside.