The invention has as its objects the provision of a bone cement composition and a bone cement composition kit for obtaining the bone cement composition having bioactivity and capable of forming a hardened material having high mechanical strength practically required, and the provision of a bone cement formed material having both bioactivity and high mechanical strength practically required and a production method thereof. The bone cement composition of the invention contains titanium dioxide particles having a median diameter of 0.5 to 7.0 µm as measured by a laser diffraction/scattering type particle size distribution analyzer and a BET specific surface area of 0.5 to 7.0 m 2 /g as measured by a nitrogen adsorption method, and a base-forming component comprising a (meth)acrylate polymer and a (meth)acrylate monomer, wherein the content of the titanium dioxide particles is 5 to 50% by mass based on the total mass of the composition.
