Abstract: In a communication processing apparatus used in a production control system, a real-time communication unit detects a diagnostic index related to communication processing and provides a notification of the possibility of unstable operation to a resource adjustment judging unit when the value of the diagnostic index exceeds a predetermined threshold. The resource adjustment judging unit judges whether a virtual processor is free when the notification is received from the real-time communication unit, instructs a virtualization unit to add the virtual processor to the virtual machine that has the possibility of unstable operation when the virtual processor is free, and instructs the virtualization unit to add a virtual processor allocated to a virtual machine with low operation priority to the virtual machine that has the possibility of unstable operation when no virtual processor is free.