To protect cables buried underground form damages caused by cutting, fires, etc., to ensure safety of power supply and communication, to reduce the weight and enhance workability, by making aggregates which are used for cable protecting members have hollow portions.

Protective members 13 for protecting cables buried in a soil layer 12 from being cut, are provided. These members 13 are composed of fire-resisting beat-resisting castable material, whose main component is aluminum oxide, and hard aggregates having hollow portions are distributed inside them. Each protective member 13 is formed into the shape of a board of specified length and is arranged along the upper part of a buried cable 11 without a gap. The soil layer 12 and the protecting members 13 are covered with a surface layer made from concrete or asphalt. The aggregates are made of alumina ceramics, and these alumina ceramics are formed into hollow aggregates. In these hollow aggregates, female screw portions are formed. Into their hollow parts, alarm members which react to vision and to sense of small are fitted.