A copolymer comprising: an unsaturated monomer having a carbosiloxane dendrimer structure represented by the following formula: wherein, Z is a divalent organic group; p is 0 or 1; R 1 and R 2 each independently represent a group selected from the group consisting of alkyl groups, aryl groups, and aralkyl groups, having 1 to 10 carbon atoms; and L 1 is a silylalkyl group, in the case of i = 1, represented by the following formula: wherein, Z and p are the same as defined above; R 1 and R 2 are the same as defined above; i is an integer ranging from 1 to 10 indicating a total number of generations of the silylalkyl group; L i+1 is a group selected from the group consisting of a hydrogen atom, alkyl groups, aryl groups, and aralkyl groups, having 1 to 10 carbon atoms, and the silylalkyl groups; however, in the case of i = c (c is an integer ranging from 1 to 10 indicating the number of generations of the silylalkyl group), L i+1 is a group selected from the group consisting of a hydrogen atom, alkyl groups, aryl groups, and aralkyl groups, having 1 to 10 carbon atoms; and in the case of i<c, L i+1 is the silylalkyl group; and a i is an integer ranging from 0 to 3; an unsaturated monomer having at least one hydrophilic group in the molecule; and an unsaturated monomer having at least one fluorine-containing organic group in the molecule; the content of the unsaturated monomer having the carbosiloxane dendrimer structure being 35 to 50% by mass of the total monomer. an unsaturated monomer having a carbosiloxane dendrimer structure represented by the following formula: wherein, Z is a divalent organic group; p is 0 or 1; R 1 and R 2 each independently represent a group selected from the group consisting of alkyl groups, aryl groups, and aralkyl groups, having 1 to 10 carbon atoms; and L 1 is a silylalkyl group, in the case of i = 1, represented by the following formula: wherein, Z and p are the same as defined above; R 1 and R 2 are the same as defined above; i is an integer ranging from 1 to 10 indicating a total number of generations of the silylalkyl group; L i+1 is a group selected from the group consisting of a hydrogen atom, alkyl groups, aryl groups, and aralkyl groups, having 1 to 10 carbon atoms, and the silylalkyl groups; however, in the case of i = c (c is an integer ranging from 1 to 10 indicating the number of generations of the silylalkyl group), L i+1 is a group selected from the group consisting of a hydrogen atom, alkyl groups, aryl groups, and aralkyl groups, having 1 to 10 carbon atoms; and in the case of i<c, L i+1 is the silylalkyl group; and a i is an integer ranging from 0 to 3; Z is a divalent organic group; p is 0 or 1; R 1 and R 2 each independently represent a group selected from the group consisting of alkyl groups, aryl groups, and aralkyl groups, having 1 to 10 carbon atoms; and L 1 is a silylalkyl group, in the case of i = 1, represented by the following formula: wherein, Z and p are the same as defined above; R 1 and R 2 are the same as defined above; i is an integer ranging from 1 to 10 indicating a total number of generations of the silylalkyl group; L i+1 is a group selected from the group consisting of a hydrogen atom, alkyl groups, aryl groups, and aralkyl groups, having 1 to 10 carbon atoms, and the silylalkyl groups; however, in the case of i = c (c is an integer ranging from 1 to 10 indicating the number of generations of the silylalkyl group), L i+1 is a group selected from the group consisting of a hydrogen atom, alkyl groups, aryl groups, and aralkyl groups, having 1 to 10 carbon atoms; and in the case of i<c, L i+1 is the silylalkyl group; and a i is an integer ranging from 0 to 3; Z and p are the same as defined above; R 1 and R 2 are the same as defined above; i is an integer ranging from 1 to 10 indicating a total number of generations of the silylalkyl group; L i+1 is a group selected from the group consisting of a hydrogen atom, alkyl groups, aryl groups, and aralkyl groups, having 1 to 10 carbon atoms, and the silylalkyl groups; however, in the case of i = c (c is an integer ranging from 1 to 10 indicating the number of generations of the silylalkyl group), L i+1 is a group selected from the group consisting of a hydrogen atom, alkyl groups, aryl groups, and aralkyl groups, having 1 to 10 carbon atoms; and in the case of i<c, L i+1 is the silylalkyl group; and a i is an integer ranging from 0 to 3; an unsaturated monomer having at least one hydrophilic group in the molecule; and an unsaturated monomer having at least one fluorine-containing organic group in the molecule; the content of the unsaturated monomer having the carbosiloxane dendrimer structure being 35 to 50% by mass of the total monomer.