PURPOSE: To produce title treated filler, by moistening an inorganic or organic filler in any desired form with a metallic compound-containing composition obtained by adding an oxidizing agent to an aqueous solution of the metallic compound, and thereby depositing the metal on the surfaces of the filler.

CONSTITUTION: A treated filler having a beautiful metallic luster is obtained by moistening (A) at least one inorganic or organic filler in any form with a metallic compound-containing composition obtained by adding at any desired point, (C) an oxidizing agent to an aqueous solution of (B) the metallic compound, and thereby depositing the metal on the surface of (A). As the component (A), a filler having a particle diameter of about 50W2,000μ, such as glass flake powder, mica or coarsely divided resin is used. As the component (B), silver is most frequency used, and copper and gold rank next to silver. A typical example of (C) is a Fehling's solution and an aldehyde method, glucose method, etc., and used in obtaining silver mirrors.