Hydrolysis and polycondensation of poly(dimethylsiloxane) (PDMS), tetraethoxysilane (TEOS), and calcium nitrate, added with tetraisopropyltitanate (TiPT) at a TiPT/(TiPT + TEOS) molar ratio of 0.15, gave a pore- and crack-free transparent monolithic organic-inorganic hybrid material. It was speculated to be composed of a Si-O-Ti-O- network modified with methyl groups, and a Ca2+ ion ionically bonded to the network. The hybrid obtained showed a high apatite-forming ability on its surface in a simulated body fluid that is indicative of high bioactivity, as well as mechanical properties such as bending strength, Young's modulus, and strain at failure, analogous to those of the human cancellous bone. This hybrid material is expected to be useful as a new type of bioactive bone-repairing material.