COMMUNICATION MONITORING APPARATUS AND COMMUNICATION MONITORING METHOD

A communication monitoring apparatus holds a communication pair model and the number of communications of a communication pair generated during, before, and after a determination target period, calculates the number of model communications of the other of the pair during the determination target period from the communication pair model and the number of communications of one of the pair, compares a value based on a difference between the number of communications of the other of the pair and the number of model communication with a threshold value, and if an abnormality is determined to have possibly occurred in a communication of the communication pair during the determination target period, based on the number of communications of the communication pair during a total time, and on the communication pair model, determine whether the abnormality has occurred in the communication of the communication pair.