Abstract: A computer system, comprising: a plurality of physical computers; and a management server for managing the plurality of physical computers, wherein at least one virtual computer operates on each of the plurality of physical computers, wherein the at least one virtual computer executes at least one piece of service processing including at least one piece of sub processing, wherein the management server is configured to calculate a required resource amount which is a resource amount of a computer resource required for the virtual computer subject to the migration based on used resource amount for the each of the plurality of the pieces of sub processing; search for a physical computer of a migration destination; and migrate the virtual computer subject to the migration to the physical computer of the migration destination.