To improve an adhesiveness of a cap stock material to a structural plastic without giving a bad effect on useful physical characteristics of the acrylic material in the cap stock material for the structural plastic (especially a polystyrene).

This acrylic composition used for the cap stock for the structural plastic in a composite material to be molded by a feed block simultaneous extrusion consists of a blend of an acrylic ester polymer with an acrylic polymer-based additive. The composite material product consisting of the structural plastic layer having a thin protective layer of a blended material consisting of the acrylic ester polymer and the acrylic polymer-based additive, and the method for producing the same product are also provided.