A system utilization rate managing device that realizes a management of a system performance and an optimization of the number of operating nodes of different performances and architectures is provided.A node maximum-performance setter of a processing device files a maximum performance of each node constituting an external system into a node maximum-performance memory section of a memory device. A resource utilization rate acquirer acquires a resource utilization rate of each node, and gives it to a virtual utilization rate calculation section. The virtual utilization rate calculation section calculates a virtual utilization rate of the system from the maximum performance of each node retained in a node maximum-performance memory section and the resource utilization rate of each node, and gives the virtual utilization rate to an output section. The output section outputs the virtual utilization rate to an output device.