A disk recording/reproducing apparatus and a disk recording/reproducing method wherein a recording disk (1) having an absolute address is provided with a program region (6) and a read-in region (7), data such as play data are recorded on the program region (6), the data are recorded on the read-in region (7) using, as catalog data, a start address data of a data unit region where the data have been recorded and a finish address data, and the data on the program region (6) are reproduced from the catalog data in the read-in region (7). An erase inhibit flag is set to the catalog data for each of the data units, whereby the erase inhibit and the erase enable are designated by the erase inhibit flag for each of the data units for the data that are recorded on the program region (6).