To obtain a viscoelastic resin compsn. which can offer a good balance among heat resistance, flexibility, adhesion, oil resistance, and creep resistance and is useful as a material alternative for vulcanized rubber by mixing a specified thermoplastic elastomer with an acrylate monomer and polymerizing the mixture.

This resin compsn. is prepd. by mixing a thermoplastic styrene elastomer with a monofunctional or polyfunctional acrylate monomer and polymerizing the mixture. Addition and mixing of an initiator followed by ultraviolet radiation to conduct polymn is pref. The use of a polyfunctional acrylate monomer is still pref. The wt. ratio of the styrene elastomer to the acrylate monomer is still pref. (95 to 60):(5 to 40).