PURPOSE: To prepare an inorg. compd. fine particle having uniform and excellent hydrophobicity and good dispersibility by dispersing the inorg. compd. fine particles in an aq. soln. having a specified content of an ionic surfactant and kept at a specified pH to prepare the aq. slurry and mixing a trialkoxysilane into the slurry.

CONSTITUTION: Inorg. compd. fine particles (e.g. titanium oxide) are dispersed in an aq. soln. contg. 0.01-10% of at least one kind of surfactant selected from a group consisting of anionic surfactant, cationic surfactant and amphoteric surfactant and kept at pH8-13 to prepare the aq. slurry. A trialkoxysilane expressed by R1Si(OR2)3 (R1 is 1-20C saturated or unsaturated monovalent hydrocarbon groups, and R2 is 1-6C monovalent hydrocarbon groups) is mixed by 5-500 pts.wt. into 100 pts.wt. of the inorg. compd. fine particle. Consequently, inorg. compd. fine particle having uniform and excellent hydrophobicity and good dispersibility is prepared.