Demand of artificial seasoning lumber is increasing in the building market because of its high production efficiency. Hybrid seasoning which combines a steam drying process with a microwave dielectric process is one of the useful methods to reduce $CO_2$ emission as well as to improve material quality. The study aims to analyze the effect of $CO_2$ reduction and economic efficiency on the hybrid seasoning in comparison with the conventional steam drying process. Life cycle analysis is used to investigate the direct and indirect $CO_2$ emissions during a life period of production facilities related to the hybrid drying system. The indirect $CO_2$ emission is estimated by the method of input-output analysis. From the analysis it is concluded that the hybrid drying system is able to reduce 0.215 million ton and to improve 6.50 billion yen if the market share of the hybrid drying system would be increased up to 25.9.