DUPLEX OPERATION SYSTEM, DUPLEX OPERATION METHOD, AND PROGRAM

A virtual machine control device 20 includes: an external disk 22 that has recorded thereon initialization information including user data and application software for each virtual machine 11; and a restart control unit 21 that, when a failure in which a reboot of an OS is executed without a restart escalation for expanding an initialization range in stages occurs in a virtual machine 110 of an active system (ACT), stops a duplexed operation, causes another general-purpose device 10x to load the initialization information for the virtual machine 110 of an active system that has stopped and to reboot an OS and also causes a virtual machine 111 of a standby system (SBY) that has stopped the duplexed operation to load the initialization information for the virtual machine 111 and to reboot an OS, and sets as an active system the general-purpose device 10x that has started up first, and sets as standby system a general-purpose device 101 that has started up later.