A composition having excellent adhesiveness to poorly adhesive materials such as polyolefins is provided. The solution is a composition comprising the following (1) to (2): (1) (meth)acrylates containing the following (1-1) to (1-3): (1-1) a (meth)acrylate having a hydroxyl group, (1-2) an alkyl (meth)acrylate, and (1-3) a (meth)acrylate having a cyclic ether skeleton, and (2) an organoboron compound. The content ratio of (1-1), (1-2), and (1-3) is (1-1):(1-2):(1-3)=(10 to 90):(5 to 80):(5 to 80) in mass ratio in 100 parts by mass of (1) (meth)acrylates.