A data retrieval system having a database storing data as a vector that has been digitized based on a keyword. The system has capability of generating a residual vector from the data to compute a covariance matrix and an eigenvector of the covariance matrix. The system further has the capability for generating and storing a set of basic vectors from the set of the computed eigenvectors, and for reading out the data and at least one of the eigenvectors from a memory. This is utilized to compute a contribution of the eigenvector to the data, and for contracting or enlarging a residual vector to store. The system selects a keyword to be used for labeling according to a similarity between the stored basic vector and the data, and a weight on the similarity so as to store the keyword in a memory.