To make easily fully utilizable much information obtained by retrieval by a learner without making it too much for the learner and to improve a learning effect by executing retrieval by using learning material data controlled by the use of a key word and forming an index map by obtaining the sum of sets of the key word of the obtained material.

A retrieval support requirement part 2 inputs a retrieved object required by the learner 1 in a computer. A language tree retrieval and control part 3 receives the retrieval requirement to the requirement part 2 and retrieves a language tree and the material in a data base. The material(primary information) is retrieved by using the key word coincident with the retrieved object out of the learning material data base 4. The material obtained by this retrieval is inputted in an index map presentation part 5, where the sum of sets of the key word is obtained to form the index map. At such a time, significance on the language tree is decided based on the appearing frequency of the key word, and a significant part, that is, a part having the high appearing frequency is segmented to make a key word appearing frequency table and perform a structural concept analysis.