PURPOSE: To complete the function of a virtual computer without assistance of an operator, by completing the function of the virtual computer at the time of stopping the operation of an OS (Operating System) on the virtual computer.

CONSTITUTION: The output processing means 3 of an operation stop message in the virtual computer processes to make the output means 4 of the operation stop message output the operation stop message of the OS on the virtual computer. Next, the stoppage of the OS on the virtual computer is informed to a virtual computer monitor by an OS operation stoppage informing means 5 on the virtual computer, and the virtual computer monitor, when receiving the information of the operation stoppage of the OS on the virtual computer, starts up a completing means 6. And the completion processing 7 of the virtual computer is started up by the completing means 6 of the virtual computer. When the completion processing of the virtual computer by the completion processing of the virtual computer is performed, the completion message output processing 8 of the virtual computer outputs the completion message of the virtual computer by the completion message output means 9 of the virtual computer.