PROBLEM TO BE SOLVED: To provide sustained release particles which are excellent, of course, in sustained release and also excellent in dispersibility, and to provide a manufacturing method therefor.SOLUTION: A method for manufacturing sustained release particles comprises steps of preparing a hydrophobic solution by dissolving a hydrophobic anti-biologically active compound with a hydrophobic polymerizable vinyl monomer, preparing an emulsifier aqueous solution by combining water and an emulsifier, emulsifying the hydrophobic aqueous solution into the emulsifier aqueous solution and conducting the miniemulsion polymerization of the polymerizable vinyl monomer of the emulsified hydrophobic solution in the presence of a polymerization initiator to prepare a polymer having an average particle size of less than 1 &mu；m and containing the anti-biologically active compound.【課題】徐放性は元より、分散性にも優れる徐放性粒子およびその製造方法を提供すること。【解決手段】疎水性の抗生物活性化合物を疎水性の重合性ビニルモノマーで溶解することにより、疎水性溶液を調製し、水と乳化剤とを配合して乳化剤水溶液を調製し、疎水性溶液を乳化剤水溶液中に乳化させ、乳化された疎水性溶液の重合性ビニルモノマーを、重合開始剤の存在下、ミニエマルション重合して、抗生物活性化合物を含有する平均粒子径１μｍ未満の重合体を生成する。【選択図】なし
