Nowadays, Precast Concrete is adopted on most of construction, because of shortening construction period and good quality. In precast concrete, steam curing is necessary for getting proper strength, but it causes much CO CO22 and economc. Therefore, on this study, by using type III cement and hardening accelerator, early compressive strength was shown 13MPa for 6hr. From the result, removal form could be shorten. Furthermore, annual CO CO22 was reduced as much as 24% and also annual cost was decreased as much as 12%.