The present invention relates to a method of preparing microspheres by using a polymer having a sol-gel transition property and microspheres prepared thereby, and more particularly, to a method of preparing microspheres by using a polymer having a sol-gel transition property and microspheres prepared thereby capable of preventing a solvent in a polymer solution for a carrier from being rapidly diffused to the aqueous medium before formation of the microspheres to reduce porosity of the microspheres and reduce surface roughness of the microspheres in order to obtain microspheres having a sphere shape, and increasing an encapsulation ratio of a bioactive substance, by using a polymer having a sol-gel transition property as a surfactant included in an aqueous medium into which a primary emulsion is injected and gelating a secondary emulsion formed after injecting the primary emulsion using the sol-gel transition property of the polymer used as the surfactant.
