Problem to be solved: to reduce the deterioration of the coating ability to the hair of the conditioner, the copolymer capable of keeping the conditioning component and the like capable of increasing the conditioning effect for a portion having a high degree of damage, the hair dressing composition containing the copolymer, and the hair cosmetic composition Provide conditioning agents and hair cleaners containing objects.Solution: (I), (II-1) and (II-2) were co polymerized, and 10% cumulative distribution particle diameter D10, 50% cumulative distribution particle diameter D50, and 90% cumulative distributed particle diameter D90 satisfy the relationship of 0.5 ≦ (d90-d10) / D50 ≦ 2.0 by measuring the particle size distribution in water. Copolymer II.(I) copolymers comprising hydrophilic vinyl monomers (a) and a unit consisting of hydrophobic vinyl monomers (B1)Vinyl monomer (c) with carboxy groupHydrophobic vinyl monomer (B2)Diagram【課題】コンディショナーの毛髪に対する塗り延し性の悪化を抑制しつつ、ダメージ度の高い部位に対してはコンディショニング成分等が留まりコンディショニング効果を高めることができる共重合体、該共重合体を含む毛髪化粧料組成物、該毛髪化粧料組成物を含むコンディショニング剤および毛髪洗浄剤を提供する。【解決手段】下記（ｉ）、(ii-1)および(ii-2)を共重合させてなり、水中での粒度分布測定による１０％累積分布粒子径Ｄ１０、５０％累積分布粒子径Ｄ５０、および９０％累積分布粒子径Ｄ９０が、０．５≦（Ｄ９０－Ｄ１０）／Ｄ５０≦２．０の関係を満足する、共重合体II。（ｉ） 親水性ビニルモノマー（Ａ）由来の構成単位と疎水性ビニルモノマー（Ｂ１）由来の構成単位を含む共重合体(ii-1) カルボキシ基を有するビニルモノマー（Ｃ）(ii-2) 疎水性ビニルモノマー（Ｂ２）【選択図】図１
