1 A data retrieval system for causing a computer to retrieve data being stored in a database, said retrieval system comprising: a database storing data as a vector digitized based on a keyword; a means for generating a residual vector from said data to compute a covariance matrix and an eigenvector of said covariance matrix, and for generating and storing a set of basic vectors from a set of said computed eigenvectors; a means for reading out said data and at least one of said eigenvectors from a memory, and for computing a contribution of said eigenvector to said data, and for contracting or enlarging a residual vector to store; and a means for selecting a keyword to be used for labeling according to a similarity between said stored basic vector and said data, and a weight on said similarity so as to store the keyword in a memory.