A high compressive strength silica mortar to be used for the installation of constructs such as building inside and outside walls, the road pavement, a slope and planting trees in the roof and manufacturing method thereof are provided. The high compressive strength silica mortar is formed of 30 to 60 wt % of silica, 40 to 70 wt % of blast furnace slag, and the 15 to 35 weight parts of polycondensation regulator for 100 weight parts of dry mortar powder of these silica and blast furnace slag, and is solidified by generating C--S--H, C-A-H, amorphous Geopolymeric Matrix{Al.sub.2O.sub.3.mSiO.sub.2.nM.sub.2O.xH.sub.2O(M=K,Na,Ca)} and Zeolite in the mortar. In particular, the high compressive strength silica mortar exhibits the compressive strength of 70.0 MPa or more by vibration forming and curing for 12.about.48 hours at 25 to 80.degree. C. before removal of form and aging for 28 days, and can save energies because a firing process is not required. Accordingly, the high compressive strength silica mortar has excellent properties compared with conventional cement concretes or polymer cements, and further shows high compressive strength in initial stage, which could not be generated in such products.