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.本發明係以提供一種可形成具有活體活性能力的同時亦具有實用上必要的高物理強度之硬化體的骨水泥組成物及為製得骨水泥組成物時之骨水泥組成物套組,以及具有活體活性能力的同時亦具有實用上必要的高物理強度之骨水泥成形體及其製造方法為目的。本發明之骨水泥組成物,其特徵為含有藉由雷射繞射/散射式粒度分布計所測定的中徑為0.5~7.0μm、藉由氮氣吸附法所測定的BET比表面積為0.5~7.0m2/g之二氧化鈦粒子,與由(甲基)丙烯酸酯系聚合物及(甲基)丙烯酸酯系單體形成的基材形成用成分,且前述二氧化鈦粒子之含有比例相對於組成物全體而言為5~50質量%。
