PURPOSE: To obtain TiO2 fine particles uniformly coated with silver by forming a silver plating film on TiO2 fine particles and reducing silver oxide remaining in the plating film to silver by using a reducing agent.

CONSTITUTION: To a water suspension of TiO2 fine particles, a surfactant (e.g. stearyltrimethylammonium chloride) is added and uniformly dispersed, and then an ammonium complex soln. of silver as a silver compd. soln. is added and enough stirred. Then, aq. formaldehyde is added as a reducing agent and the mixture liquid is heated at 50-80°C for electroless plating to form a uniform silver plating film on the TiO2 fine particles. Then, SBH is added as a reducing agent to the water suspension to reduce silver oxide remaining in the plating film to silver.