[en] To increase technical reliability in geological disposal technology of high-level radioactive waste, JAEA have been conducting R and D activities in the fields in the repository engineering, performance assessment (PA) of the geological disposal system, and geoscientific study. In the field of R and D on the repository engineering, laboratory experimental studies at Tokai Research Center are carried out by engineering-scale and non-radiogenic experiments. The studies on performance assessment include more realistic model development with extensive computer analyses and acquisition of basic data concerning the chemical properties and migration behavior of radionuclides under geological disposal conditions. The information obtained from the Underground Research Laboratories (URLs) is used to provide a realistic condition of geological environments for these studies. The R and D studies are also carried out for TRU waste. A particular JAEA R and D activity is to promote the projects of two Underground Research Laboratories (URLs): one at Mizunami city, in crystalline rock and the other at Horonobe town, in sedimentary rock. In the present stage (2nd R and D phase) of the URL projects, the investigation are being carried out during the excavation of shafts and drifts. Data obtained from the investigations will serve to verify and refine the results from the surface-based investigations and characterize the evolution of the geological environment during drift excavation. The research on natural processes, such as fault and volcanic activities, is also conducted to provide better understanding of long-term stability on the geological environment. JAEA has initiated a project to develop the next generation of novel knowledge management system (KMS) to develop and manage the technical knowledge base for supporting implementers and regulators. This knowledge base includes all technical achievements by the JAEA as well as know-how and experience which have been accumulated in individual technical experts. This document serves the annual report which summarizes the results and major topics in the JAEA R and D activities carried out in the Japanese fiscal year of 2006 (April 2006 - March 2007). (author)