PURPOSE: To perform the fractionation of knowledges to each user according to its attributes such as ability, occupation, and interest in the knowledge acquiring action of learning by heart of knowledges by adding a proper rank of a plurality of ranks of importance degree as the importance degree of the knowledge to be acquired.

CONSTITUTION: A knowledge importance degree judging part 12 has a knowledge importance degree judging rule, judges the importance degree for each of knowledges to be presented of the knowledges stored in a knowledge data base 13 by use of the knowledge importance degree judging rule on the basis of the user information 101 received from an user information input part 10, and forms importance degree information 102. The knowledge data whose importance degree is not 0 is transmitted to an image presenting part 15 as the knowledge number information 103 and the importance degree information 102 together with the user information 101. The image presenting part 15 has a presented image forming rule, takes out the knowledge from the knowledge data base according to various pieces of information received from the knowledge importance degree judging part 12, and selects the constituting element data used for the image for displaying the knowledge from a constituting data base 14.