Classification hierarchy regeneration system, classification hierarchy regeneration method, and classification hierarchy regeneration program

A classification hierarchy regeneration system is provided, wherein when a new classification hierarchy is generated by restructuring an existing classification hierarchy, a classification hierarchy in view of hierarchical relationship of classifications and a classification hierarchy integrating classifications of the same meaning can be efficiently generated. The clustering means clusters a data group associated with a hierarchical classification, and generating a classification group, i.e., a group obtained by extracting a classification satisfying a condition defined in advance from classifications corresponding to respective data in a cluster. The cooccurrence degree calculation means calculates a degree of cooccurrence of two classifications selected from the classification group. The classification hierarchy regeneration means regenerates the hierarchy of classification based on the classification group and the degree of cooccurrence.