THE PRESENT INVENTION RELATES TO A SURFACE COATED POSITIVE ELECTRODE ACTIVE MATERIAL, A PREPARATION METHOD THEREOF, AND A LITHIUM SECONDARY BATTERY INCLUDING THE SAME. MORE SPECIFICALLY, IT RELATES TO A POSITIVE ELECTRODE ACTIVE MATERIAL OF WHICH SURFACE IS COATED WITH A NANOFILM INCLUDING POLYIMIDE (PI) AND CARBON BLACK, A PREPARATION METHOD THEREOF, AND A LITHIUM SECONDARY BATTERY INCLUDING THE SAME. THE POSITIVE ELECTRODE ACTIVE MATERIAL OF WHICH SURFACE IS COATED WITH THE NANOFILM ACCORDING TO THE PRESENT INVENTION IS CAPABLE OF PREVENTING DIRECT CONTACT OF THE POSITIVE ELECTRODE ACTIVE MATERIAL WITH AN ELECTROLYTE THEREBY SUPPRESSING A SIDE REACTION BETWEEN THE POSITIVE ELECTRODE ACTIVE MATERIAL AND THE ELECTROLYTE, AND AS A RESULT, A LIFESPAN PROPERTY OF A LITHIUM SECONDARY BATTERY USING A POSITIVE ELECTRODE INCLUDING THE SAME MAY BE SIGNIFICANTLY IMPROVED, AND PARTICULARLY, A LIFESPAN PROPERTY AND CONDUCTIVITY ARE CAPABLE OF BEING ENHANCED UNDER A HIGH TEMPERATURE AND HIGH VOLTAGE CONDITION.