Network monitoring system, network monitoring method, and program

This network monitoring system which monitors virtual network function is characterized by being provided with: a prediction means for acquiring necessary information for detecting abnormalities in a virtual network function provided on an NFV infrastructure and predicting performance information of the newly-provided virtual network function to be monitored; a generation means for generating abnormality determination rules to be a standard for determining whether actual performance information of the virtual network function lies within an acceptable range determined from the predicted performance information; a determination means for determining abnormalities using the actual performance information of the virtual network function, and the abnormality determination rules; and an output means for outputting an abnormality notification when a determination by the determination means is abnormal.