A hypervisor sets all physical areas in an allocation area, which is allocated to a virtual machine from within a physical memory and is configured from a plurality of physical areas, to a write protect mode. In a case where a physical processor identifies that the write-destination area from the virtual machine is in the write protect mode, the hypervisor manages the write-destination area as an updated area, and cancels the write protect mode of the write-destination area. At a certain point in time, the hypervisor copies data inside the updated physical area from within the allocation area to a storage area (a copy area) that differs from the allocation area. In a case where a prescribed failure is detected in the physical area, the hypervisor restores data from the copy area.