There are X-ray contrast properties, the polymerizable composition novel excellent transparency and cured product thereof, and composite materials containing the ground product of the cured product. Having (A) X-ray imaging property, an inorganic oxide having an average particle size of 100nm or less, (B) surface modifier, (C) a polymerizable compound, a polymerizable composition containing a polymerization initiator (D), these further composite containing a ground product of the cured product and the cured product obtained by polymerizing.X線造影性があり、且つ透明性に優れる新規な重合性組成物、その硬化物および硬化物の粉砕物を含有する複合材料。(A)X線造影性を有する、平均粒子径100nm以下の無機酸化物、(B)表面改質剤、(C)重合性化合物、さらに(D)重合開始剤を含む重合性組成物、これらを重合して得られる硬化物、および硬化物の粉砕物を含有する複合材料。
