PURPOSE: To obtain the titled fine spheres having excellent expandability, dispersion properties and retarded scattering properties, by coating the outer surface of fine spheres expandable when heated which enclose a blowing agent in a thermoplastic high polymer material with a high-boiling hydrocarbon, and then drying the fine spheres to attain a specific moisture content.

CONSTITUTION: The outer surface of 1W50μ diameer fine spheres foamable when heated which enclose a blowing agent (e.g. neopentane or dichlorofluoroethane) in a thermoplastic high polymer material (e.g. PVC or vinylidene chloride-acrylo- nitril copolymer) is coated with 0.5W10wt% one or more high-boiling hydrocarbons (e.g. octene or liquid paraffin) which are difficulty volatile or nonvolatile at a room temperature and show flow properties at 40°C or lower. Thereafter, the fine spheres are dried to attain a moisture content of 10wt% or less in a gaseous atmosphere at a temperature 5°C or more lower than the foaming temperature of the fine spheres.

EFFECT: A foam having excellent blendability with a resin emulsion or solution, being bulky and rich in a three-dimensional sense, is obtained.