A sound-proof wall made of FRP in the form of a sound-proof wall panel that includes a core and skin members made of FRP positioned on both sides of the core and whose weight per nit area is within the range of 10-60 kg/m.sup.2; and a method of producing the same. This sound-proof wall, though light in weight, has a superior sound insulation property and will never corrode because it is made of FRP. Further, it has a high degree of freedom of engineering design including sound-proof property, design, and shape, capable of producing a desired sound-proof wall with case. Further, since it has a high specific strength, it is possible to attain a drastic weight reduction while retaining the necessary strength, and facilitate working, shorten construction time, and reduce construction cost.