When gathering words through a dictionary growth process, a dictionary growth unit (102) stores information indicating through what process of input and output a word has been gathered in a gathering process memory unit (107). Then, a clustering unit (103) classifies the word that has been gathered by the dictionary growth process into clusters on the basis of information recorded in the gathering process memory unit (107). Next, a type determination unit (104) determines whether a word comprising a cluster is of the same type as a seed word or of a different type, for each cluster into which the word has been classified, on the basis of information recorded in the gather process memory unit (107). In addition, an output unit (105) associates information indicating the gathered word, the cluster to which the word belongs and whether the cluster is of the same type as the seed word or of a different type, and displays such.