Our community is facing serious Aging Society especially in Japan. We have investigated in one of daycare centers which are facilities for elderly care. As the result, we realized that communication is needed for its own sake in these facilities and active communication can cure even depression and dementia. Therefore we propose to cope with these problems using a robot as a communication activator in order to improve group communication. We define group communication as one of types of communication which is formed by several persons. This time, we focus on a recreation game named "Nandoku. " Nandoku is a quiz which can be describedas group communication with a master of ceremony (MC). The system always selects its behavior and target (aparticipant in the game) to maximize "communication activeness. " Communication activeness is defined as amount of several panelists'(ordinary three: A, B, C) participation, which are calculated with panelists' face direction using camera information. For instance, if participant A is not fully participating by not making eye contact, the system is expected to select one of the behaviors such as "Can you answer, Mr.A?" to encourage A to participate in the game. We experimented with the system in a daycare center. As the result, obvious increase in participation was observed. That offers evidence that the robot can serve a practical role in improving the group communication as a communication activator especially for entertainment use.