PURPOSE: To improve strength and fire resistance and facilitate washing at fouling by wrapping the outer face of a lengthy plate-like core material made of polycarbonate resin by means of fire resisting cloth.

CONSTITUTION: A salt core material 11 is formed out of polycarbonate resin plate. Next, a cloth cover 12 made of cloth treated with flameproofing by organic halogen series chemical or cloth having self-extinguishing property such as nonflammable acryl fiber is provided. Next, the cover 12 is stuck on both aides of the core material 11 through a binder layer 13, and the end edge parts are welded so as to from welder deposited parts 14. Further if necessary, only the lower face may be stuck so as to improve adaptability to wind and heat insulating property. Hereby, beuding resistance and the like can be improved, washing can be easily performed with a washer and the like, and fire resistance can be improved because polycarbonate resin has self-extinguishing property.