To provide a technique related to further effective utilization of a muddy soil such as lake and marsh sludges, river sludges, harbor dredging sludges, outlet deposits of thermal power plants or sludges accumulated near the outlet.

This hydraulic composition is produced by utilizing a muddy soil prepared by reducing the moisture content to ≤85% by dehydrating treatment as a raw material, baking the raw material at 1,200-1,500°C, providing a baked material containing 10-40 wt.% of one or more of C11A7 CaCl2, C11A7 CaF2 and C3A and one or more of C2S and C3S, pulverizing the resultant baked material to ≥2,000 cm2/g Blaine specific surface area, adding and mixing a gypsum therewith.