The access device 100 designates a file ID without relating different address spaces of an access device 100 and a nonvolatile memory device 200 with each other and manages a data storing state only in a physical address space in the nonvolatile memory device 200. The access device 100 sends a transfer rate to the nonvolatile memory device 200 by using a transfer rate sending part 121. A filling rate calculation part 251 calculates a filling rate of physical block corresponding to a guaranteed speed required by the access device 100. A remaining capacity corresponding to the transfer rate is obtained by using the calculated filling rate and is sent to a remaining capacity receiving part 122 of the access device 100.