Anaerobically curing adhesive sealing composition

An anaerobically curing adhesive sealing composition comprising (A) a mono(meth)acrylate monomer represented by formula (I) ##STR14## wherein R.sub.1 represents a hydrogen atom or a methyl group;

• and R.sub.2 represents ##STR15## (B) a (meth)acrylate prepolymer having a urethane structure in the main chain thereof and having an average molecular weight of at least 10,000 and (C) a (meth)acrylate prepolymer having a urethane structure in the main chain thereof and an average molecular weight of from 500 to 5,000, said methacrylate prepolymer (B) being the reaction product of an isocyanate terminated polyurethane prepolymer, prepared from a polyether polyol and an organic diisocyanate, with a (meth)acrylate of a polyhydric alcohol having active hydrogen which is a mono(meth)acrylate of a dihydric alcohol or a (mono)methacrylate or di(meth)acrylate of a trihydric alcohol and said (meth)acrylate prepolymer (C) being a polyester diol or a polyester polyol-diisocyanate reaction product having isocyanate terminal groups reacted with a (meth)acrylate of a polyhydric alcohol as defined above, and wherein the polyether polyol employed to prepare component (B) is at least one compound of the formula (II), (III), (IV) or (V);
• ##STR16## wherein n.sub.1 and n.sub.2 each represents an integer of from 1 to 5.