PURPOSE: To provide the titled compsn. producing molding products with a smooth surface and a high adhesive power to hydrophilic material and substrate, prepared by adding a diene rubber to a thermoplastic styrene/diene block copolymer.

CONSTITUTION: 3W30pts.wt. diene rubber is added to 100pts.wt. thermoplastic styrene/diene block copolymer. The dienes are e.g., butadiene and isoprene. The diene rubber includes styrene/butadiene, polyisoprene, natural and acrylonitrile/ butadiene rubbers. When the diene rubber content is less than 3pts.wt., the compsn. shows poor adhesion to hydrophilic material and when it exceeds 30pts.wt., a molding product shows severe plastic deformation and is no longer suitable for practical use. Molding products formed from the compsn. have low-level cold flow and swelling and consequently good dimentional stability and can be bonded readily and strongly to paper, cloth, wood and other hydrophilic materials with a water-soluble adhesive.