A cosmetic for hair comprising a co-modified organopolysiloxane represented by the following general formula: R 1 a L 1 b Q c SiO (4-a-b-c)/2 wherein R 1 represents a monovalent organic group, with the proviso that L and Q are excluded therefrom, a hydrogen atom or a hydroxyl group; L 1 represents a silylalkyl group having a siloxane dendron structure, in the case of i = 1, represented by the following general formula: wherein R 2 represents a substituted or non-substituted, and linear or branched monovalent hydrocarbon group having 1 to 30 carbon atoms; R 3 independently represents an alkyl group having 1 to 6 carbon atoms or a phenyl group; Z represents a divalent organic group; i specifies a number of generations of said silylalkyl group, represented by L 1, in the case in which the number of generations of said silylalkyl group, which is the number of repetitions of said silylalkyl group, is k, i is an integer ranging from 1 to k, and the number of generations k is an integer ranging from 1 to 10; L i+1 is said silylalkyl group in the case of i < k, and L i+1 is R 3 in the case of i = k; and h i is a number ranging from 0 to 3; Q represents a hydrophilic group which binds to a silicon atom via a linking group with two or more valances and comprises at least one hydrophilic unit selected from hydrophilic units represented by the following structural formulae to: -C r H 2r -O- wherein r is a number ranging from 1 to 6, wherein W represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, wherein W represents the same group as defined above, and and each of a, b and c is independently a number having the following range: 1.0 ≤ a ≤ 2.5, 0.0001 ≤ b ≤ 1.5, and 0.0001 ≤ c < 1.5. R 1 represents a monovalent organic group, with the proviso that L and Q are excluded therefrom, a hydrogen atom or a hydroxyl group; L 1 represents a silylalkyl group having a siloxane dendron structure, in the case of i = 1, represented by the following general formula: wherein R 2 represents a substituted or non-substituted, and linear or branched monovalent hydrocarbon group having 1 to 30 carbon atoms; R 3 independently represents an alkyl group having 1 to 6 carbon atoms or a phenyl group; Z represents a divalent organic group; i specifies a number of generations of said silylalkyl group, represented by L 1, in the case in which the number of generations of said silylalkyl group, which is the number of repetitions of said silylalkyl group, is k, i is an integer ranging from 1 to k, and the number of generations k is an integer ranging from 1 to 10; L i+1 is said silylalkyl group in the case of i < k, and L i+1 is R 3 in the case of i = k; and h i is a number ranging from 0 to 3; Q represents a hydrophilic group which binds to a silicon atom via a linking group with two or more valances and comprises at least one hydrophilic unit selected from hydrophilic units represented by the following structural formulae to: -C r H 2r -O- wherein r is a number ranging from 1 to 6, wherein W represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, wherein W represents the same group as defined above, and and each of a, b and c is independently a number having the following range: 1.0 ≤ a ≤ 2.5, 0.0001 ≤ b ≤ 1.5, and 0.0001 ≤ c < 1.5.