To provide a material for an earth and sand structure, having strength equal to or more than that of a cement-based solidification agent, and to provide a slope protecting construction method using the same.

This material for the earth and sand structure is produced through a first process for kneading calcined magnesia with one or more kinds of earth and sand selected from sandy substances and earthy substances, together with one or more kinds of modifiers selected from a coagulant, guar gum, and an absorbent polymer, a second process for mixing hemihydrated gypsum and the calcined magnesia, the hemihydrated gypsum, or the calcined magnesia into the kneaded earth and sand and kneading them, and a third process for further mixing the calcined magnesia, water in a prescribed amount, one or more kind of admixing agents selected from an AE water reducing agent, a high-performance water reducing agent, a high-performance AE water reducing agent, a retardant, citric acid, a soil dispersing agent, magnesium sulfate, phosphoric acid, sodium citrate, an iron salt, a soluble silicic acid, soluble silicates, and soluble aluminas, and one or more kind of admixing materials selected from fly ash, silica fume, slag, sepiolite, calcium carbonate, and stone dust into the kneaded earth and sand and kneading them. The material for the earth and sand structure is placed on a protecting surface on site.