[en] JAEA is developing a 'Knowledge Management System' for vast quantities of data or information arising from various sources relevant to the geological disposal programs in Japan. The geological disposal project is taking a stepwise approach to selecting a disposal site and, to the approval and licensing, construction, operation and closure of a repository. It is a long-term project required approximately 100 years. In this paper, in order to structuralize, as knowledge, the results of R and D on geological disposal technologies of high-level radioactive wastes, the knowledge management approach was first reviewed. The paper is followed by descriptions of the technical characteristics, procedure to carry out a plan, and education of geological disposal technologies such as knowledge management etc. The structuring of the knowledge base and the knowledge management system including the construction of safety case were described. (S. Ohno)