A security control method for an optical disk drive comprises a security information reading step and a security information-determining step. In the security information reading step, security information associated with data to be read is read from a plurality of locations on an optical disk. In the security information-determining step, correct security information is determined by comparing fragments of the security information read from the plurality of locations and then by selecting a security information fragment with the highest frequency. The correct security information is used in processing of the data to be read.