This is to provide a polymer crosslinking agent which is capable of improving affinity for ester oil.
The polymer crosslinking agent is a (meth)acrylic-based graft silicone which comprises (meth)acryl-based repeating units represented by the following formulae (I), (II) and (III) as a main chain, and an unsaturated bond(s) and an organopolysiloxane structure at the side chain. Also, the high molecular weight polymer is an addition polymerization product of the polymer crosslinking agent and an organohydrogen polymer, and a composition is a material in which the high molecular weight polymer is swollen by a liquid oil agent.