Abstract: A work area detection unit detects the work area in which a user is interested and a user viewpoint calculation unit extracts viewpoint information from the work area. In a dynamic communication group generation unit, the current viewpoint information of each user is accumulated in a user viewpoint information storage unit, a group generation unit generates the group information based on the similarity to the accumulated viewpoint information every time the viewing information is accumulated. In a dynamic communication session control unit, a group information storage unit accumulates the group information, a communication session generation unit generates the environment to assure the communication for all members of each group based on the group information and a communication session deletion unit deletes the group information of the group of only one member.