The method which gives a low crystalline hydroxyl carbonated apatite forming ability to originally non-bioactive high crystalline hydroxyapatite surface was newly developed. The granules of trabecular bovine bone, which had a size range from 212 to 1000 μm, were defatted, deproteinized, and then heat-treated at 1000 oC for 3 hours to remove organics completely. They were treated with the mixed solution of calcium chloride and calcium hydroxide in Soxhlet’s apparatus at 100 oC for 3 days and then dried completely. Low crystalline hydroxyl carbonated apatite was observed to occur on the surface of high crystalline hydroxyapatite granules after soaking them into the simulated body fluid (SBF) for 1 week. This method is likely to have a potential to be used as a new process to give a bioactivity to originally non-bioactive materials.