It is provided a storage system, comprising a storage device for storing data and at least one controller for controlling reading/writing of the data from/to the storage device. The at least one controller each includes a first cache memory for temporarily storing the data read from the storage device by file access, and a second cache memory for temporarily storing the data to be read/written from/to the storage device by block access. The processor reads the requested data from the storage device in the case where data requested by a file read request received from a host computer is not stored in the first cache memory, stores the data read from the storage device in the first cache memory without storing the data in the second cache memory, and transfers the data stored in the first cache memory to the host computer that has issued the file read request.