Polystyrene (PS)/poly(ethylene glycol dimethacrylate) composite polymer particles containing hinokitiol (HT) were produced by suspension polymerization for ethylene glycol dimethacrylate droplets by the dissolution of HT and PS in poly(vinyl alcohol) aqueous solution. The composite particle had a hollow structure in which HT was included. The evaporation rate of HT from the composite particles became slower than that of pure HT. (C) 2003 Wiley Periodicals, Inc.