PURPOSE: To restart the processing for data transfer.

CONSTITUTION: A command is inputted from a command input part 1-1, its restart designation is decided by a command processing part 1-2, an instruction for transferring data from a transfer origin storage device part 1-5 to a transfer destination storage device part 1-6 is issued to an input/output processing part 1-4, an address in which the data transfer is completed is stored by an address managing part 1-3, and by the instruction issed by the input/output processing part 1-4, the data is transferred from the transfer origin storage device part 1-5 to the transfer destination storage device part 1-6. At the time of designating its restart, the data transfer processing is restarted from the address stored in the address managing part 1-3, and the data is transferred from the transfer origin storage device 1-5 to the transfer destination storage device part 1-6.