The value of an open event is in active communication betweenparticipants. However, it is difficult to look for those who have a common interest or a common friend. You would miss an opportunity to speak directly to your SNS friends or to those who have common SNS friends, unless you notice that there are such participants and you recognize them. This paper proposes a participant managerial system for using the human relations in SNS in an actual event site. Each participant makes his registration to an event using his SNS ID. In the event site on the day, the participant only has to touch his mobile terminal to an NFC tag. The participant and his SNS are bound by this action. The organizer as well as the participants can understand the background and the interests of each participant using SNS information. NFC tag provides real time attendance-and-absence status of the participants. It is expectable that the proposed system promotes exchange between participants.