Abstract: Rare earth is an indispensable element in Japan’s cutting-edge fields such as renewable energy.Japan is the world’s third largest rare earth consumer, with its imports share 82% from China, accounting for 40% of China’s total rare earth exports.Japan itslef said, “Japan has been highly dependent on China’s cheap rare earth.” Since 2000, Japan has been seeking for countermeasures to ensure the stable supply of rare earth.In particular, after 2010, China has stepped up restrictions on export measures, leading Japanese governments and sectors to worry about its rare earth supply and the sustainability of hi-tech development.In recent years, Japan has utilized the advantages of its marine exploration and development technology to study marine rare earth resources for exploration, development as well as related modeling experiments.It aims to provide Japan with a stable supply of rare earth, maintaining international competitiveness of manufacturing industry, advantages on developing new uses, industries and other aspects.This paper introduces the discovery of Japanese marine rare earth, the investigation and evaluation of the rare earth sediments around Minamitorishima Island, which lasted three years by Japan Oil, Gas and Metals National Corporation(JOGMEC).The research and evaluation of the rare earth sediments, the investigation and study on technical aspects such as mud collecting, raising-up and smelting procedures.The related economic evaluation can be somewhat valuable for understanding Japan’s discovery, exploration and development of ocean rare earth.