A storage system (1) effectively manages the total capacity of hard disk drives (44) to store block-basis data and file-basis data with a shared storage medium and a managing means (30) for managing all the storage areas in the storage medium. When block data and address are input through a fiber channel port (50), a block data input/output means (10a) converts its data format to a data format that is internally applied by the storage system (1). When file data and address are input through an Ethernet port (52), a file system (20) converts its data format to the data format internally applied by the storage system (1), such as the block data format. The file system (20) derives the address of a logical volume from the received address information and translates file data to block data. The managing means (30) derives the address of a logical volume (35a, 35b) to which to write block data from the address information delivered from the block data input/output means (10a). The managing means (30) translates this address or the address passed from the file system (20) to a physical address and writes data to or read data from a hard disk drive (44) with the physical address.