An access device provided in a host device and configured to control reading or writing of data from or to a memory, in a communication system including a data recording device and the host device that are wirelessly connected to each other, the access device comprising: the memory configured to store data; and a device controller configured to send and receive a data control right between the data recording device and a central controller provided in the host device, the data control right being an exclusive right to execute the reading or the writing of data that is managed by a file system provided in the memory; characterized in that the device controller is configured to: when having received a request to interrupt transfer of data from the central controller provided in the host device while data is being transferred from the data recording device after the data control right has been granted to the data recording device, release the data control right from the data recording device, and have the data recording device determine whether or not mismatching has occurred in file system management information for data stored in the memory; and return the data control right to the data recording device when it is determined that mismatching has occurred in the file system management information, and the data recording device is configured to: release the data control right after eliminating the mismatching in the file system management information according to the returned data control right. the memory configured to store data; and a device controller configured to send and receive a data control right between the data recording device and a central controller provided in the host device, the data control right being an exclusive right to execute the reading or the writing of data that is managed by a file system provided in the memory; characterized in that the device controller is configured to: when having received a request to interrupt transfer of data from the central controller provided in the host device while data is being transferred from the data recording device after the data control right has been granted to the data recording device, release the data control right from the data recording device, and have the data recording device determine whether or not mismatching has occurred in file system management information for data stored in the memory; and return the data control right to the data recording device when it is determined that mismatching has occurred in the file system management information, and the data recording device is configured to: when having received a request to interrupt transfer of data from the central controller provided in the host device while data is being transferred from the data recording device after the data control right has been granted to the data recording device, release the data control right from the data recording device, and have the data recording device determine whether or not mismatching has occurred in file system management information for data stored in the memory; and return the data control right to the data recording device when it is determined that mismatching has occurred in the file system management information, and the data recording device is configured to: release the data control right after eliminating the mismatching in the file system management information according to the returned data control right.