Control server, virtual server distribution method

When plural virtual servers are distributed to plural physical servers, efficient distribution is performed in terms of the processing capacity of the physical servers and their power consumption. Firstly a second load of each virtual server in future is predicted based on a first load in a prescribed time period up to the present of each of the plural virtual servers. Next, the schedule is determined to distribute the plural virtual servers to the plural physical servers based on the second load of each virtual server so that a total of the second loads of one or a plurality of the virtual servers distributed to a physical server is within a prescribed range of proportion with respect to processing capacity of the physical server. Furthermore, the distribution is instructed (execution of redistribution) in accordance with the schedule.