A COMPUTER SYSTEM, RESOURCE MANAGEMENT SERVER OF A COMPUTER SYSTEM, AND RESOURCE MANAGEMENT METHOD OF A COMPUTER SYSTEM

A computer system that achieves effective utilization of physical servers' resources in a virtual client system is provided. In the virtual client system, the present invention obtains operation information about virtual machines, obtains access information indicating whether a user has logged on to the virtual machines or not, judges from connection information whether the user is using the virtual machines or not, calculates the capacity of the virtual machine(s) which are active, but is not accessed by the user, based on the capacity of resources used by the virtual machine(s), and then identifies the virtual machine(s) used by users from those not used by the users.