Multibranched polymer and method for producing the same

A multibranched polymer comprising a structure represented by formula (III):

• where:
• C represents a carbon atom,
• X4 and X5 each independently represents a linking group containing any atom of Groups 14 to 16 in the Periodic Table,
• Y4 represents:
• a group having a structure represented by formula (IV):
• where:
• T1 represents a divalent electron attractive group represented by formula (t11) or (t21):
• where:
• Z11 represents an oxygen atom, a sulfur atom, or a group represented by N-r71, wherein r71 represents a hydrogen atom, a C1-C6 alkyl group, a phenyl group which may have a substituent, an alkylcarbonyl group, a phenylcarbonyl group which may have a substituent, an alkylsulfonyl group, or a phenylsulfonyl group which may have a substituent,
• R20 represents a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C7-C12 aralkyl group, an aryl group, an ester group, or an acyl group,
• R21 represents a hydrogen atom, a C1-C6 alkyl group, a C7-C12 aralkyl group, an aryl group, an ester group, or an acyl group, and the symbol ● represents a substitution position of a halogen atom;
• or
• a group having a structure represented by formula (V):
• where:
• R22 represents a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C7-C12 aralkyl group, an aryl group, an ester group, or an acyl group,
• R23 represents a hydrogen atom, a C1-C6 alkyl group, a C7-C12 aralkyl group, an aryl group, an ester group, or an acyl group, and
• the symbol ● represents the substitution position of a halogen atom,
• R14 represents a hydrogen atom, a C1-C6 alkyl group, an aryl group which may have a substituent, a halogen atom, or a C1-C6 alkoxyl group,
• n7 and n8 each independently represents an integer of 0 or 1 or more, wherein when n7 and n8 each is 2 or more, X4(s) and X5(s) may be the same or different,
• m3 represents 3 or 4,
• groups represented by the formula:
• —(X4)n7—Y4-Q4 may be the same or different, and
• Q4 represents an arm moiety having a repeating unit derived from a polymerizable unsaturated bond.