A traffic feature information extraction method including a regular expression process, a clustering process, and a feature information extraction process. The regular expression process extracts an item set in advance from a traffic log and represents a partial character string included in the item in a regular expression based on a predetermined rule. The clustering process clusters an entry of the traffic log represented in the regular expression. The feature information extraction process extracts, as traffic feature information of each of clusters, an entry having a minimum total sum of distances among entries included in the clustered traffic logs.