Method and apparatus for managing a parental level of an optical disc can allow a user to set a parental level of a data stream recorded and stored on a rewritable optical disc or write-once optical disc, and can record and manage the set parental level as navigation information such as for the optical discs. The method and apparatus allow the user to conveniently set or change the parental level of the data stream, refer to the parental level recorded and managed therefore, and carry out a parental locking operation such that children or teenagers cannot arbitrarily reproduce a data stream of an adult program. Further, a parental grade code, a supplemental parental grade code or if the parental code was generated using parental management information previously supplied by the user can be determined. Accordingly, an authorized user can determine whether the previous set grade code is changed illegally.