The global demand for energy is increasing. Among the energies available, LNG (liquefied natural gas) is drawing increasing attention for its relatively low emission of CO₂ at combustion, compared to petroleum and coal. Mitsubishi Heavy Industries, Ltd. (MHI) started developing LNG carriers in the 1970s. Since delivering its first LNG carrier in 1983, MHI has developed low BOR (boil-off rate) techniques, sophisticated automation systems, re-liquefaction plants, winterization systems, and other advanced technologies for application to actual ships. MHI is still building highly reliable and economical LNG carriers. The company is now constructing advanced LNG carriers with two kinds of tank system, including a spherical tank type and membrane type. The knowledge collected based on MHI's actual achievements is being used to develop next-generation technologies for the construction of large ships, winterized ships, and highly efficient steam turbine ships.