Nippon Kaiji Kyokai, known as ClassNK or NK, is a ship classification society actively engaged in a growing range of ship related activities and services. These activities aimed at contributing to promoting the protection of human life and property at sea as well as protection of the marine environment.

ClassNK has earned an outstanding reputation for its long-standing dedication to safeguarding life and property at sea and preventing marine pollution through the establishment of universally recognized standards for the design, construction and maintenance of ships and other marine structures.

The Head Office is located in Tokyo and in Chiba, Japan, and there are branch offices at the major Japanese ports and overseas offices throughout the world.