To easily provide a method for producing a (meth)acryloyl-terminated polyisobutylene polymer not only without using an expensive reagent or an industrially hard-to-obtain reagent but also without depending on a multistage inefficient reaction scheme.

The method for producing the (meth)acryloyl terminated polyisobutylene polymer uses a one-step reaction of a halogen-terminated polyisobutylene polymer obtained by living cation polymerization and a compound having a (meth)acryloyl group and a carbon-carbon double bond.