The present invention relates to a method for preparing microsphere and microspheres produced by thereby. More particularly, the present invention relates to a method for preparing a polymeric microsphere comprising the steps of: mixing a water-insoluble organic solvent with a dispersion solvent mixing a polymer compound, a drug and a water-insoluble organic solvent so as to prepare a dispersed phase mixing the dispersed phase with the dispersion solvent mixed with the water-insoluble organic solvent so as to prepare an emulsion and adding a base or an acid to the prepared emulsion so as to remove the water-insoluble organic solvent from the emulsion and a polymeric microsphere thereby, and a composition for drug delivery comprising the microspheres. In the inventive preparation method, it is possible to conveniently prepare a drug-containing polymeric microsphere within a short time using a small amount of water, with the generation of a minimized amount of waste solution without a requirement of a conventional solvent-evaporation or solvent-extract ion process. Also, since a low concentration of remaining solvent within a prepared polymeric microsphere can be maintained, it is effective in preparation in sustained-release type medicines.
