To prevent cement particle from precipitating even in the case of the application of seawater and to decrease a construction cost by reacting sodium silicate known as an accelerator for cement with brine to form cloudy sol, by adjusting its concentration and by dispersing cement in the sol.

This cement milk, where cement particles in the liquid don't precipitate and the viscosity is low and a construction cost is low, is prepared by adding 50-60 kg sodium silicate to 1,000 kg brine and 200 kg cement. The brine is pref. seawater and may be artificial sea water prepared by dissolving salt contents in freshwater, or a diluent including seawater. The salt contents in the brine may be various ones (Ca, Fe, Al, K or the like). The cement milk is obtained by reacting brine including artificially combined water in a preferred content with sodium silicate to form sol, by stirring it to form uniform, white sol having low viscosity and by dispersing cement in it.