The present invention relates to a method for preparing microspheres and microspheres prepared thereby, more particularly to a method for preparing a polymeric microsphere, including preparing an emulsion including a polymer compound, a drug, a water-insoluble organic solvent and a dispersion solvent and adding to the prepared emulsion a base or an acid to remove the water-insoluble organic solvent from the emulsion, a polymeric microsphere prepared thereby, and a composition for drug delivery including the microsphere. According to the present invention, a drug-containing polymer microsphere may be prepared quickly and simply without the solvent evaporation or solvent extraction process, thereby reducing water consumption and minimizing wastewater generation.