A high-density optical disc such as BD-RE (Blu-ray Disc Rewritable) or BD-ROM, and a recording/reproducing method thereof are disclosed. Diverse additional information such as disc reflectivity information, disc layer information or disc type information is efficiently recorded in a particular information field included in a data unit recorded on the burst cutting area of a high-density optical disc or a particular 1-byte address field included in an address unit recorded on the high-density optical disc so that it can be read when the high-density optical disc is loaded in an optical disc apparatus or when a data recording or reproducing operation for the high-density optical disc is carried out. Accordingly, it is possible to achieve optimal optical power control and automatic gain control or identification of a current position, while enabling a normal data recording or reproducing operation corresponding to the type of the optical disc.