A star polymer comprising a core portion and an arm portion, wherein the arm portion includes a first generation composed of a polymer chain and a second generation composed of a polymer chain formed at the outer shell of the first generation, the number of arms of the second generation is larger than the number of arms of the first generation, the first generation composed of the polymer chain is a polymer chain derived from a monomer having a polymerizable double bond, a ratio of a weight average molecular weight (Mw) to a number average molecular weight (Mn), (Mw/Mn), of the star polymer is within a range from 1.001 to 2.50, the core portion is a core portion including a skeleton represented by formula (VIII): wherein D represents (CH 2) q, or a p-phenylene group, q represents an integer from 0 to 3, or a core portion represented by the following formulas: the first generation composed of the polymer chain in the arm portion is a styrenic polymer, the link between the arm of the first generation and the arm of the second generation is represented by formula (XIII): wherein and represent a polymer chain, X 1 represents a halogen atom, and Z 3 represents a group containing at least one carbon atom, formula: wherein and represents a polymer chain, X 2 represents a halogen atom, and Z 4 represents a group containing at least one carbon atom, or formula: wherein and represent a polymer chain, X 3 represents a halogen atom, R a represents a hydrogen atom or a C1-C6 alkyl group, R b represents an organic group, Z 5 represents a group containing at least one carbon atom, and k represents any integer of 1 or more. the number of arms of the second generation is larger than the number of arms of the first generation, the first generation composed of the polymer chain is a polymer chain derived from a monomer having a polymerizable double bond, a ratio of a weight average molecular weight (Mw) to a number average molecular weight (Mn), (Mw/Mn), of the star polymer is within a range from 1.001 to 2.50, the core portion is a core portion including a skeleton represented by formula (VIII): wherein D represents (CH 2) q, or a p-phenylene group, q represents an integer from 0 to 3, or a core portion represented by the following formulas: the first generation composed of the polymer chain in the arm portion is a styrenic polymer, the link between the arm of the first generation and the arm of the second generation is represented by formula (XIII): wherein and represent a polymer chain, X 1 represents a halogen atom, and Z 3 represents a group containing at least one carbon atom, formula: wherein and represents a polymer chain, X 2 represents a halogen atom, and Z 4 represents a group containing at least one carbon atom, or formula: wherein and represent a polymer chain, X 3 represents a halogen atom, R a represents a hydrogen atom or a C1-C6 alkyl group, R b represents an organic group, Z 5 represents a group containing at least one carbon atom, and k represents any integer of 1 or more. the first generation composed of the polymer chain in the arm portion is a styrenic polymer, the link between the arm of the first generation and the arm of the second generation is represented by formula (XIII): wherein and represent a polymer chain, X 1 represents a halogen atom, and Z 3 represents a group containing at least one carbon atom, formula: wherein and represents a polymer chain, X 2 represents a halogen atom, and Z 4 represents a group containing at least one carbon atom, or formula: wherein and represent a polymer chain, X 3 represents a halogen atom, R a represents a hydrogen atom or a C1-C6 alkyl group, R b represents an organic group, Z 5 represents a group containing at least one carbon atom, and k represents any integer of 1 or more.