Disclosed is a method for preparing an anode active material comprising a core composed of a crystalline carbon-based material, and a composite coating layer comprising (a) mixing a precursor for a raw material of one or more materials selected from the group consisting of low crystalline carbon and amorphous carbon with silicon oxide enabling intercalation and deintercalation of ions, followed by purification, to prepare a mixture for coating, (b) mixing the mixture for coating with a crystalline carbon-based material to prepare a core-shell precursor comprising the raw material mixture for coating applied to the core composed of the crystalline carbon-based material, and (c) baking the core-shell precursor to carbonize the raw material of the one or more materials selected from the group consisting of low crystalline carbon and amorphous carbon into the one or more materials selected from the group consisting of low crystalline carbon and amorphous carbon.