An update management system for performing update management of communication service applications, comprising: one or more virtualized infrastructure managers, VIM, configured to manage each of virtualization resources including a physical server in which one or more virtual network functions, VNF, are realized, each VNF constituting a virtual communication processing node configured to execute a communication service, and generate a new version VNF in said physical server based on an instruction to generate the new version VNF; a service monitor configured to monitor the communication service executed by the VNF; and a virtual communication function management node, VNFM, configured to instruct the VIM to generate the new version VNF, generate old and new correspondence data indicating correspondence between the new version VNF and an old version VNF, and including at least a VNF type, a number of the new version VNF and a number of the old version VNF and notify the service monitor that there is startup of the new version VNF based on the old and new correspondence data, and instruct the VIM to perform network switching from the old version VNF to the new version VNF; and wherein the VIM is further configured to execute network switching to the new version VNF based on the instruction for said network switching; wherein the VNFM is further configured to identify the new version VNF and the old version VNF based on the old and new correspondence data, when there is an abnormality in a new version communication service executed by the new version VNF detected through monitoring by the service monitor, and request the VIM to execute network switching-back from the new version VNF to the old version VNF; and wherein the VIM is further configured to execute the network switching-back from the new version VNF to the old version VNF based on a request for said network switching-back. one or more virtualized infrastructure managers, VIM, configured to manage each of virtualization resources including a physical server in which one or more virtual network functions, VNF, are realized, each VNF constituting a virtual communication processing node configured to execute a communication service, and generate a new version VNF in said physical server based on an instruction to generate the new version VNF; manage each of virtualization resources including a physical server in which one or more virtual network functions, VNF, are realized, each VNF constituting a virtual communication processing node configured to execute a communication service, and generate a new version VNF in said physical server based on an instruction to generate the new version VNF; a service monitor configured to monitor the communication service executed by the VNF; and a virtual communication function management node, VNFM, configured to instruct the VIM to generate the new version VNF, generate old and new correspondence data indicating correspondence between the new version VNF and an old version VNF, and including at least a VNF type, a number of the new version VNF and a number of the old version VNF and notify the service monitor that there is startup of the new version VNF based on the old and new correspondence data, and instruct the VIM to perform network switching from the old version VNF to the new version VNF; and instruct the VIM to generate the new version VNF, generate old and new correspondence data indicating correspondence between the new version VNF and an old version VNF, and including at least a VNF type, a number of the new version VNF and a number of the old version VNF and notify the service monitor that there is startup of the new version VNF based on the old and new correspondence data, and instruct the VIM to perform network switching from the old version VNF to the new version VNF; and wherein the VIM is further configured to execute network switching to the new version VNF based on the instruction for said network switching; wherein the VNFM is further configured to identify the new version VNF and the old version VNF based on the old and new correspondence data, when there is an abnormality in a new version communication service executed by the new version VNF detected through monitoring by the service monitor, and request the VIM to execute network switching-back from the new version VNF to the old version VNF; and identify the new version VNF and the old version VNF based on the old and new correspondence data, when there is an abnormality in a new version communication service executed by the new version VNF detected through monitoring by the service monitor, and request the VIM to execute network switching-back from the new version VNF to the old version VNF; and wherein the VIM is further configured to execute the network switching-back from the new version VNF to the old version VNF based on a request for said network switching-back.