Unused deep geothermal resources in Japan have been estimated to have great potential, and tapping them would be an effective method for significantly increasing the capacity of geothermal power generation. However, our understanding of geothermal systems that exist at depths of over 2,000 m is still very limited. Therefore, in order to delineate characteristics of deep geothermal reservoirs and establish a desirable direction for the development of deep geothermal resources, NEDO started a six-year research project entitled "Deep-seated Geothermal Resources Survey" within the framework of the New Sunshine Project of the Ministry of International Trade and Industry (MITI) in FY 1992