A learning device generates a character class series abstracting a structure of a predetermined character string included in each of requests to the server which have been generated in a predetermined period. Also, for each of the combinations of the predetermined identification information and the character class series included in the requests, the learning device calculates a score for update which becomes higher as the number of times of appearance of the combination is increased and becomes higher as the appearance of the combination is continued. Based on the score for update, the learning device updates the profile of each combination for determining whether the request is an attack or not.