A polymer comprising a styrene-based monomer and t-butyl methacrylate,
wherein a proportion of the styrene-based monomer in the polymer is 30%
by mol to 90% by mol and the polymer has a functional group represented
by the following formula (1) which includes a maleimidyl group:
##STR00001## wherein in the formula (1), X represents --O-- or --NH-- and
Q represents a spacer group. A ligand immobilization support comprising
the polymer.