A storage system manages the total capacity of a shared storage medium to store block-basis data and file-basis data. When block data and its address are input through a fiber channel port, an inputloutput unit converts its data format to a data format that is internally applied by the storage system. When file data and its address are input, a file system converts its data format to a block data format internally applied by the storage system. The file system derives a file logical volume address from the received file address and translates file data to block data. A managing unit derives the address of a block logical volume from the block address delivered from the input/output unit. The managing unit translates block logical volume address or the file logical volume address to a physical address, and writes data to or reads data from the shared storage medium.