PURPOSE: To always display by extracting detail information in the neighborhood of an information element being remarked at present and the whole main information by setting the size of weight corresponding to the significance of each information element which forms a heirarchically classified and managed information group.

CONSTITUTION: A significance managing part 5 manages the significance (distance in a hierarchical depth direction and distance from a remarked picture element) at every information element stored in a data base part 2, and changes the significance by calculating the distance from a remarked element at every instruction of the change of the remarked element by an instruction input part 4. When the weight is set corresponding to the significance of each information element which forms the hierarchically classified and managed information group, the weight is set so that the more depth or distance increased, the less the weight is set for the information element up to a hierarchy with specific depth or up to specific distance from the information element remarked by the user, and also, the weight of the information element on the hierarchy lower than the specific depth or separated far from the specific distance is set so as to be kept constant.