molten pertroleum resin molten polyethylene urethane prepolymer unsaturated polyester resin and the like two or more kinds of said visco elastic materials may be mixed together in the present invention fig5 and fig6 relate to the second embodiment of the present invention referring now to fig5 and fig6 a masking member 110 comprises a panel 111 consisting of a polystyrene foam the same as the first embodiment and grooves 112 the same as the first embodiment are formed on both sides of said panel 111 a primer layer 115 is formed on a side of said panel 111 and an adhesive layer 113 is formed on said primer layer 115 said adhesive layer 113 is covered with a release sheet 114 the same as the first embodiment said primer layer 115 prevents said adhesive layer 113 soaking into said panel 111 since said panel 111 consists of the polystyrene foam and the surface of said panel 111 is porous and said primer layer 115 is formed by laminating the film of a plastic such as polyethylene polypropylene vinyl acetate ethylene copolymer polyvinylchloride and the like by heating or adhesive or by coating with an emulsion or a solution of a synthetic resin such as acrylic resin polyvinyl.