Abstract: A storage device realizing an improvement in rewrite endurance of a nonvolatile memory and an improvement in data transfer rate of write and read is provided including a nonvolatile memory 101; a volatile memory 106 for storing file management information of the nonvolatile memory 101; a controller 103 for controlling the nonvolatile memory 101 and the volatile memory 106; and a power supply maintaining unit 105 for supplying power to the nonvolatile memory 101, the volatile memory 106, or the controller 103 upon power shutdown. The controller 103 reads the file management information in the nonvolatile memory 101 upon power-on and writes the same in the volatile memory 106, and read and write operations are performed based on the file management information in the volatile memory 106, and the file management information in the volatile memory 106 is written in the nonvolatile memory 101 upon power shutdown.