A group-determination-table generating device for generating a group determination table used for grouping information sent from each communication device according to the degree of attention of the user of each communication device in a communication system having at least three communication devices, comprising:
- statistics means for reading attention-degree patterns indicating the degree of attention which the user of each communication device pays to information sent from other communication devices and group structure patterns indicating the group state of each user, and for collecting statistics on the attention-degree patterns and the group structure patterns;
- determination means for determining the correspondence between each attention-degree pattern and one of the group structure patterns from the statistics obtained by the statistics means;
- and
- determination-table generating means for generating a group determination table indicating attention-degree patterns and group structure patterns for which the correspondence is determined by the determination means.