The computer system has a plurality of physical server devices, a plurality of physical storage devices, and a management server device, and when migrating at least one of a plurality of first virtual server devices to another physical server device, the management server device compares at least one physical server device in which the plurality of first virtual server devices are disposed after the migration, with at least one physical server device in which a plurality of second virtual server devices are disposed, to calculate a first evaluation value, and also compares at least one physical server device in which the plurality of first virtual server devices are disposed after the migration, with at least one physical server device in which a plurality of third virtual server devices are disposed, to calculate a second evaluation value. Based on the first evaluation value and the second evaluation value, the management server device issues an instruction to migrate the first virtual storage device to the other physical storage device.