A biodegradable material that bonds to hard tissues such as bones and teeth is urgently needed for medical and dental applications. However, such materials are not available in today's clinical practice of orthopedics and dentistry. Therefore, we synthesized biodegradable phosphorylated pullulan to develop a biomaterial that combines primary properties such as high biocompatibility, good bonding potential to hard tissue, high strength, biodegradability, and osteoconductivity. The pharmacopoeial polysaccharide pullulan was chemically functionalized with dihydrogen phosphate groups. Phosphorylated pullulan was formed network by adding calcium ion, making the composite less soluble in water. Adhesive force measurement revealed that adhesiveness of the pastes before setting can be controlled through optimization of additives. In addition, histological evaluation revealed that phosphorylated pullulan-based composite possesses high biocompatibility. These results indicate that phosphorylated pullulan can be used as a key material for regeneration and reconstruction of bone and tooth.