CONSTITUTION: This hardening material composition is obtained by incorporating 10-60 pts.wt. of (A) quick-setting clinker composition powder with 0.1-40 pts.wt. of cement powder and 10-60 pts.wt. of gypsum powder. In this case, the composition A is prepared by incorporating (B) a clinker composition comprising a clinker predominant in 12CaO.7Al2O3, 0.1-9wt.% of Fe2O3 and 0.1-9wt.% of CaF2 with 0.1-50wt.% of 2CaO.SiO2-based calcium silicate phase and/or 2CaO.Al2O3.SiO2-based calcium aluminosilicate phase (and not 3CaO.SiO2-based calcium silicate phase). By using this hardening material, the embedding work period for clay pipes, etc., can be shortened, and works in redigging the ground again for repairing clay pipes, etc., can be facilitatedened.