PURPOSE: To economically produce a silica useful for reinforcing silicone by mixing a silica suspension, a hydrophobic agent and an org. solvent and separating an obtained liquid phase and spherical silica.

CONSTITUTION: The silica suspension obtained by neutralizing an alkali metal silicate soln. with an acidifying agent such as sulfuric acid and gaseous CO2 and precipitating the silica and an organosilicone compd. (e.g. trimethylsilane) as the hydrophobic agent are mixed for 1-2hr while keeping pH in constant to obtain a mixture. Then an org. solvent (e.g. methylisobutyl ketone) is added and mixed to the mixture so that a ratio of an amount (l) of the solvent and a weight (kg) of SiO2 may be 1-5, and after precipitating and separating a spherical silica, the silica is washed at need and an hydrophobic precipitated silica having a density of ≥0.15, ≥20% water wetability, ≤5% water absorption, ≥0.08mm average size, ≥50m2/g BET surface area and ≥40m2/g CTAB surface area is obtained.