The importance of referring to international rules concerning the development of marine minerals in the ocean areas under national jurisdiction has ever been identified. Internationally, no specific rules have been presently developed to directly regulate marine minerals development in the ocean areas under national jurisdiction. In recent years, the importance of the provisions of Part XII of the United Nations Convention on the Law of the Sea, and in particular the importance to have and follow proper procedures in carrying out such activities, has been increasingly recognized. Norway is currently under the process to open its continental shelf for mineral activities. Its Seabed Minerals Act clearly states that an environmental, social and economic impact assessment and consultation should be conducted at the stage of the opening process, on the other hand no such statement is found in the Mining Act in Japan. In order to implement marine minerals development on the basis of international understanding, it is necessary to continue to pay attention to the extant related international law and law-making trend.