In order to consider how to strengthen and foster core ocean technologies, current state of ocean technology in Japan is reviewed. The framing of ocean technologies used in the offshore oil and gas development is investigated, and linkage between these technologies and ocean technologies necessary for the ocean renewable energy utilization, the sea floor mining and the methane hydrate development which are expected to be industrialized in Japanese exclusive economic zone (EEZ) in the future. The history of development of ocean technologies in Japan is reviewed to know strength and weakness of Japan's ocean technologies. Summarizing these results, it is found that there is strong linkage between ocean technologies used in the offshore oil and gas development and future projects deployed in Japanese EEZ, and it is important to invest governmental funds in a comprehensive and systematic fashion for developing those core technologies. It is also emphasized that it is important to apply the environment technology and IT to the ocean technology for strengthening Japan's core ocean technologies.
