To obtain the subject macromonomer having a multi-olefin structure and useful as a material for polyfunctional polymerization initiator precursors, cross-linking agents for synthesizing branched olefin resins and UV irradiation film forming and fixing agents, and a polymeric additive.

This multi-branched macromonomer having a multi-olefin structure is expressed by the formula {M is CH2-C6H4-CH2, (CH2)n [(n) is 2-12], (CH2CH2O)n [(n) is 1-6]; X is Cl, Br or OH, R is an olefin residue}. The macromonomer has a structure in which numbers of styrene or aryl monomer structures polymerizable by free radical, ion and coordination are bonded in a nonlinear polymer skeleton.