PURPOSE: To improve moldability by mixing inorg. materials in such a manner that CaO+P2O5, B2O3 and other inorg. components attain specific molar ratios, heating the mixture at a prescribed temp to meet and then cooling the same.

CONSTITUTION: Raw materials, such as CaCO3, H3PO4 and H3BO3 are so weighed as to obtain a compsn. contg. 60 to 80mol% (hereafter %) CaO+P2O5, 10 to 30% B2O3 and 0 to 10% other inorg. components, such as Mg, Ba, Al, Ti and Zr, and having 1.5 to 3.0 Ca/P. These raw materials are mixed by a wet process using a solvent, such as methanol, and thereafter, the solvent is removed by heating. The mixture is then put into a crucible where the mixture is heated to 1000 to 1300° and is melted for a prescribed period of time; thereafter, the mixture is allowed to cool. The inorg. compsn. capable of easily molding and having bioaffinity and which has a high content of β-tricalcium phosphate crystals is obtd.