The present invention relates to a resin-coated powder material prepared by coating at least one organic resin selected from a silicone resin and a fluorocarbon resin; a coating composition prepared by mixing a zinc oxide needle-like single-crystal inorganic powder with a silicone resin coating composition and/or fluorocarbon resin coating composition; and a substrate surface-modifying method which comprises coating an inorganic powder dispersion containing, as essential components, a needle-like single-crystal inorganic powder and a resin onto a plastics substrate or inorganic substrate to impart water-repellency to the surface of the substrate.