an object of the present invention is to provide an osteogenic biomaterial which achieves long - term sustained release and localized functional expression of a substance which promotes the formation of bone tissue . the present inventors have found out that a nanogel efficiently encloses an osteogenesis promoting substance to suppress the substance from diffusion into blood , and that the nanogel functions as a carrier for local administration of the osteogenesis promoting substance . furthermore , they have found out that the osteogenesis promoting substance - containing nanogel can be cross - linked with a water - soluble polymer to allow sustained release of the osteogenesis promoting substance at a local area over a long period of time . based on these findings , the present invention was completed . the osteogenic biomaterial of the present invention which contains the osteogenesis promoting substance and the nanogel shows osteogenesis promoting activity over a long period of time , and can be used as a preventive and therapeutic agent against bone diseases .