Importance-level calculation device, output device, and recording medium in which computer program is stored

A non-transitory computer-readable medium storing a computer program making a computer realize a function of:

• computing, when a first alert is notified in response to detection of an abnormality in a communication network to be monitored, an importance level of the first alert, based on a characteristic that is included in communication information that has caused the first alert but is not included in communication information related to one or more second alerts having been notified prior to the first alert;
• wherein
• when computing the importance level, obtaining the importance level, based on originalities for all first N-grams included in the communication information and the number of all the first N-grams, and the importance-level calculation means obtains the originality of the first N-gram based on an elapsed time from an appearance time at which the first N-gram being the same as second N-grams having appeared in the past to a detection time at which the abnormality is detected.