PURPOSE: To manufacture a laminate structure of extremely superior resistance to chemicals, non-toxic and of extremely superior strength by constituting a structure of polyolefin layer and fiber reinforced plastic layer between which a polystyrene foamed layer is inserted.

CONSTITUTION: A polyeste fiber non-woven material 2 is wound on the surface of cylindrical polyethylene layer 1 molded by rotational molding and heat softened by, for instance, frame treating or the like. Then, an FRP layer 3 is formed on the non-woven cloth 2 wound on the polyethylene layer 1. For example, a glass fiber string is soaked in a mixed liquid of unsaturated polyester and styrene at the ratio of 1:1 and also mixing a curing agent therein, and wound on the non-woven cloth 2, or the glass fiber and mixed liquid are mixed and sprayed, or else a glass fiber knit material is wound on the non-woven cloth 2, on which the mixed liquid is applied for impregnation. A polystyrene foamed material layer 4 is formed by heat softening a polystyrene foamed material sheet in the state that the FRP layer 3 is not cured completely. Further, the FRP layer 5 is laminated over the polystyrene foamed layer 4.