CO₂ emission control is recognized as the essential issue related to the greenhouse effect, especially since demand for energy increasing. Use of Liquefied Natural Gas (LNG) must be expanded because it produces less CO₂ emission than any other fossil fuel. Worldwide, approximately 90 million tons of LNG are transported by sea in 1999. Mitsubishi Heavy Industries, Ltd. (MHI) has developed LNG Carriers (LNGCs) since the early 1970s, and has been introducing many technical innovations, such as an insulation system with lower boil-off-rate (BOR), and a sophisticated automation system, in order to enhance their reliability and economy. MHI is building its latest LNGCs with both major containment systems, namely, the spherical tank type and the membrane tank type, and MHI is the No. 1 shipbuilder of LNGCs in the World. Given the safe and reliable operation of LNGCs over the past thirty years, the economy of LNG transportation has become a topic of increasing attention for the LNG supply chain. MHI will continue to lead the way by building future LNGCs that incorporate new technical advancements such as size enlargement, standardization and alternative propulsion plants.