To save labor for polishing and the like for a tooth tip part, and the like of a non-circular deformed gear so as to improve production efficiency.

In a transmission device 10, which is constructed of a substantially elliptic or polygonal driving gear 12 and a substantially elliptic or polygonal driven gear 14 geared to the driving gear 12, when the driving gear 12 is rotated at a fixed angular speed, the driven gear 14 is rotated at an irregular angular speed. Rotating bodies 20, which can be freely rotated at least one of the normal/reverse rotating direction of the gears 12, 14, are arranged in either of tip parts to which the gears 12, 14 are geared.