Provided are a plasticizer composition, a resin composition and a method of preparing the same. Particularly, a plasticizer capable of improving physical properties such as plasticizer efficiency, migration, tensile strength, elongation rate, stress migration and light resistance, which are required for sheet formulations, when used as a plasticizer for a resin composition by improving poor physical properties generated due to a structural limitation thereof, and a resin composition including the same are provided.