PROBLEM TO BE SOLVED: To provide a composition for repairing a hard tissue having low toxicity to a living body and a kit for repairing a hard tissue in which a residual monomer amount is reduced.SOLUTION: There are provided a composition for repairing a hard tissue that contains a monomer (A), polymer powder (B) and a polymerization initiator (C), in which the polymer powder (B) contains polymer powder (B-x) having an aspect ratio of 1.10 or more, and a cumulative ratio of powder particles having an aspect ratio of 1.00 or more and less than 1.10 in the whole powder particles among each component contained in the composition for repairing the hard tissue is 65 cumulative percent or less； and a kit for repairing a hard tissue that has a member in which each component of the monomer (A), the polymer powder (B) and the polymerization initiator (C) contained in the composition for repairing the hard tissue are divided into three or more components with an arbitrary combination, and are stored.SELECTED DRAWING: NoneCOPYRIGHT: (C)2020,JPO&INPIT【課題】残留モノマー量を低減した低生体為害性の硬組織補修用組成物及び硬組織補修用キットを提供する。【解決手段】モノマー（Ａ）、重合体粉末（Ｂ）及び重合開始剤（Ｃ）を含む硬組織補修用組成物であって、重合体粉末（Ｂ）が、アスペクト比が１.１０以上の重合体粉末（Ｂ－ｘ）を含み、硬組織補修用組成物に含まれる各成分のうち粉末粒子全体におけるアスペクト比１.００以上１.１０未満の粉末粒子の累積比率が６５累積％以下である硬組織補修用組成物；並びに、この硬組織補修用組成物に含まれるモノマー（Ａ）、重合体粉末（Ｂ）及び重合開始剤（Ｃ）の各成分が、任意の組合せで３つ以上に分割されて収容された部材を有する硬組織補修用キット。【選択図】なし
