A recording/reproducing apparatus is provided which can write continuously a file of large-capacity at high-speed. A record area of HDD is provided with a disk cache area for temporarily storing data to be written. The disk cache area is defined as a area that is not used by a host apparatus (3) in an LBA space, and the disk cache area is disposed in an area with a high transfer rate such as an outer circumferential area of a disk (10). A file transferred from the host apparatus (3) is written in the disk cache area, and the file is transferred from the disk cache area to a usual user area during an idle period to release the disk cache area and prepare for next transfer data write.