To produce a high quality gear efficiently, and to clean the working environment thereof at a low cost with a device such as a dust collector.

This device comprises a shot peening device 1 providing shot peening treatment for a gear 5 that have undergone tooth forming and surface- hardening treatment, a barrel treatment device 2 placed adjacent to the shot peening device 1 and providing barrel treatment for a gear having undergone shot peening treatment from the shot peening device 1, and a gear transporting device 3 placed adjacent to the shot peening device 1 and the barrel treatment device 2 and supplying a gear having undergone the shot peening treatment from the shot peening device 1 to the barrel treatment device 2.