Block Copolymer

A block copolymer comprising a polymer segment A having a unit represented by Formula 4 below and polymer segments B and C different from the polymer segment A,

• wherein the block copolymer comprises a structure in which each of the polymer segments is connected in a form of B-A-C:
• wherein, R is hydrogen or an alkyl group having 1 to 4 carbon atoms, X is a single bond, an oxygen atom, a sulfur atom, —S(═O)2—, a carbonyl group, an alkylene group, an alkenylene group, an alkynylene group, —C(═O)—X1— or —X1—C(═O)—, where X1 is an oxygen atom, a sulfur atom, —S(═O)2—, an alkylene group, an alkenylene group or an alkynylene group, and Y is a monovalent substituent comprising a ring structure to which a chain having 8 or more chain-forming atoms is linked.