This paper presents a method of novel plasma treatment for fine particles by the atmospheric-pressure glow (APG) discharge, in which particles were circulated and repeatedly plasma-treated at atmospheric pressure. Using this method, plasma-polymerized tetrafluoroethylene (TFE) film formations on the porous granulated silica particles of 152 mu m mean diameter were investigated. The XPS C(1s) spectrum of the treated surfaces deconvoluted into five peaks, which indicates that the films on the particles were composed of highly branched and crosslinked fluoro-carbon segments. The film-coated particles were very hydrophobic. Sound absorption measurements showed that the film-coated particles had a larger elastic coefficient than that of the untreated particles, indicating that dense films were coated on the porous silica particles.