Soft-nanotechnologies are based upon the synthesis technologies of nanomaterials and construction technologies of nanostructures by life forms. They are expected as new preparation methods for biomaterials that could be recognized as regular extracellular matrices (ECM) in our body by cells. We applied the soft-nanotechnology to synthesis of artificial bones made of HAp and collagen with bone-like nanostructure and examined their physical and biological properties. The nanocomposite obtained indicates bone-like nanostructure. Computer simulation and FT-IR suggested that the self-organization of HAp and collagen is based on chemical interaction between calcium ions on HAp surface and carboxy groups on collagen. After implantation in rats and dogs, the nanocomposites are resorbed by osteoclasts followed by osteogenesis; therefore, the nanocomposites are recognized as bone in the living body. Resorption rate can be controlled by crosslinkage. We also prepared sponge-like elastic porous body by gel-lyophilization technique using additional small amount of collagen solution. Bone tissue reactions of it are the same as the nanocomposites as prepared. The nanocomposites are now in clinical research in Japan to be commercialized in near future by Pentax Co.