Chitosan nanofibre-apatite nuclei composites obtained by mixing apatite nuclei which possess high apatite-forming ability with chitosan nanofibre have been expected to be novel bone restorative materials with suitable properties such as light weight, low coefficient of thermal expansion, high mechanical strength, biocompatibility and bioactivity. In this study, the authors prepared three types of apatite nuclei by changing the reaction time aimed to optimise their crystallinity and fabricated their composites with chitosan nanofibre. In order to evaluate the bioactivity in vitro, the authors tested apatite-forming ability in simulated body fluid. As a result, the materials showed enough apatite-forming ability in a short time by mixing chitosan nanofibre and apatite nuclei with extremely low crystallinity and their high reactivity in simulated body fluid.