Composite plastics in which silica was dispersed homogeneously were prepared from a resole-type phenol resin and a silica-sol using water glass. The silica (10-50 nm) was dispersed into resin particles of 2-20 lm in size. The powder that was obtained (nanocomposite filler) and a curing reagent were then mixed, and the resulting mixture was processed by using heat and pressure to yield plastics containing nanocomposite fillers. The coefficients of friction factor of the resulting plastics composites decreased by half and the amount of wear that they suffered decreased to just one tenth of that of the unfilled material, while their wear-resistance was greatly improved. The new plastics displayed good sliding properties, while also maintaining good fluidity.