Mitigation of seismic loads by seismic isolation technology is very promising for enhanced safety and economy of the next generation nuclear reactor, through rationalized and simplified design of structures, systems and components. The horizontal base isolation with laminated rubber bearings is a proven technology and its application has been widely spread including nuclear facilities. On the other hand, significantly increased benefit of mitigated seismic loads is expected with three-dimensional (3D) seismic isolation, since the seismic loads are inherently three-dimensional and the vertical component of the seismic load sometimes plays an important role in the structural design of reactor components. From these points of view, a large scaled research project has been undertaken for the development of 3D seismic isolation technologies, under the sponsorship of the Ministry of Economy, Trade and Industry of Japanese government. Within this program, two types of 3D seismic isolation systems were selected appropriate for next nuclear power plant. One is the 3D entire building base isolation technology, and another is the vertical isolation device for main component with horizontally entire building base isolation technology. There were three promising ideas of the 3D entire building base isolation technology, i.e., “rolling seal type air spring”, “hydraulic 3D isolation system”, and “cable reinforced air spring”. Then one idea was chosen from these three ideas for next development. Also, “vertical component isolation system with coned disk springs” is under developing for vertical isolation for main plant components. This paper overviews the entire development program and the current status of these 3D isolation systems.