A shared server 40 includes an active virtual machine 41 where a sufficient amount of resources are allocated to an operation of an application system and a standby virtual machine 42 that starts with a minimum amount of resources. When it is predicted that a provisioning request is generated, a standby construction determining unit 22 previously executes provisioning on a standby virtual machine 42, and performs a start of an OS and an application or a setting change of a network apparatus. A provisioning determining unit 23 changes the resource allocation amounts of the active virtual machine 41 and the standby virtual machine 42, allocates a sufficient amount of resources to the standby virtual machine 42, registers the standby virtual machine 42 as a target of load balancing in a load balancer 11, and executes provisioning.