PURPOSE: To enable a unit body not only to rationally absorb/shield sonic waves but also to absorb electromagnetic waves by a method wherein the body is formed of structural material which contains balls that are conductive containing metal pieces, large in specific gravity, and covered with binder resin high in elasticity and empty spaces surrounded with the adjacent contact points of the balls left as continuous voids.

CONSTITUTION: Lead or steel balls 1 used as sound insulating material and coated with two-pack type urethane rubber or chloroplene rubber are cured and bound together into the structural material of an absorbing body which contains continuous voids 4. The structural material is manufactured through such a process that urethane resin main agent and urethane resin hardening agent are mixed together into a binder liquid first, then graphite is added to the binder liquid and uniformly mixed, and metal whiskers and lead balls as conductive additive are added to the binder liquid in a mixer, uniformly disperse as kneaded, and hardened. When radio waves impinge on an absorbing body, generate electric energy is grounded to a previously installed grounding through the intermediary of conductive binder.