AbstractGlobal regime on Greenhouse Gas (GHG) reduction has changed at the end of 2009. Clean Development Mechanism (CDM) has revealed some critical defects and all participants recognize less profit than they had expected and are disappointed with agricultural fields. There are 2 issues that brought less profit - Price of GHG and Verification before Certified Emissions Reductions (CERs) would be issued by the CDM Executive Board and credited to the participants of a project. Therefore, at the end of 2009, Bilateral Offset Mechanism has launched, which could be considered to be revised CDM. However, in the agricultural field, no precedent has been shown between Japan and Asian countries. Under Kyoto Protocol Regime, United Nation CDM executive board has adopted baseline method and not adopted Life-cycle Assessment (LCA) method. Under Bilateral Offset Mechanism, however, LCA method might be adopted, if 2 participants agreed LCA method in stead of baseline method.5 scenarios would be compared on GHG reduction by LCA method, because LCA method might be used under Bilateral Offset Mechanism or Post Kyoto Protocol Regime.Reduced greenhouse gas (GHGs; CO2, CH4, and N2O) emissions of the alternative systems instead of conventional systems were estimated by using LCA method preparing for Bilateral Offset Mechanism or Post Kyoto Protocol (post-Kyoto) regime. If GHG from the agricultural sector in developed countries would be taken into account on Bilateral Offset Mechanism or post-Kyoto Protocol Regime, reduced GHG from the agricultural sector in developed countries could be available.