One or more random access-type storage devices comprise a volume group and a journal volume. The volume group contains a volume pair configured from a primary volume and a secondary volume. Whenever data is received from a host device, this received data is written in the primary volume, a journal containing the write sequence of the data and the data is produced, and the journal is written in a journal volume. A plurality of journals accumulated in a journal volume are written in a sequential access-type storage device. Based on the write sequence recorded in each of the plurality of journals recorded in the sequential access-type storage device, the data of the journals is restored to the primary volume for storing the data and to a secondary volume from which the volume pair is configured.