PROBLEM TO BE SOLVED: To suppress scattering of a soil improving material during operation, to show strength early, and to suppress outflow of soil particles, when improving the soil property of deposit soil containing salinity and moisture.SOLUTION: A soil improving material is obtained by allowing a water-absorptive porous granular body to hold a water-soluble component used as a supply source of calcium ion and sulfate ion. The porous granular body is preferably a PS ash granulated substance. Further, porous particles obtained by burning diatomaceous earth can be also used as the porous granular body.
