Composition for hard tissue repair and kit for hard tissue repair

A composition for hard tissue repair comprising a monomer (A), a polymer powder (B) and a polymerization initiator (C), wherein

• the polymer powder (B) comprises a polymer powder (B-x) having an aspect ratio of 1.10 or more, and
• the cumulative ratio of powder particles having aspect ratios of 1.00 or more and less than 1.10 in all of the powder particles contained in the composition for hard tissue repair is 2.5 cumulative % or more, and 65 cumulative % or less,
• the monomer (A) is a (meth) acrylate-based monomer,
• the polymer powder (B) is a polymethyl (meth) acrylate powder,
• the polymerization initiator (C) comprises an organic boron compound (c1), the blending amount of the monomer (A) is 10-45% of the total mass of the components (A) to (C),
• the blending amount of the polymer powder (B) is 54.9-80% of the total mass of the components (A) to (C), and
• the blending amount of the polymerization initiator (C) is 0.1-10% of the total mass of the components (A) to (C).