To meet CO2 emission regulation, this study describes the present state of CO2 reduction technology and the effect of the regulation on power industry. In Japan, R&D investment is actively continuing through a long-term R&D project, along with trying to meet the reduction demand by the ways of energy saving and abroad business. EU has made a lot of investments in increasing the effciency of power generation and developing alternative energy sources. The US is making provision of the portion of reduction by using energy saving program and emission trading, and the current DOE-driven program is addressing the development of cost-effective power systems. In the country, the research to reduce CO2 emission has been mainly driven by the government and research institute supported by the government. Meanwhile, if the reduction obligation imposed on Portugal which is the least strict condition will be enforced in Korea, it is likely that about 50 running power plants should be stopped or shut down after 2015, in spite of voluntary reduction efforts such as conversion to clean fuels, etc. according to the government's long-term electric power need and supply plan.