Three kinds of data, i.e., a keyword frequency-of-appearance, a document length, and a keyword weight, are produced. Then, a document profile vector and a keyword profile vector are calculated. Then, by independently performing the weighted principal component analysis considering the document length and the keyword weight, a document feature vector and a keyword feature vectors are obtained. Then, documents and keywords having higher similarity to the feature vectors calculated with reference to the retrieval and extracting conditions are obtained and displayed.