This study investigated the effect of social networking services (SNS) and related PR activities, as managed by the convention organizer, to the organization- public relationship and attendance satisfaction. In review of the results of this study, the meaningful results are deducted as such that convention organizer SNS PR activities of the demonstrate a positive effect on the organization-public relationship and attendance satisfaction. Also verified is that the recognition on public relationship and attendance satisfaction between SNS users and SNS non users (Homepage or Newsletter user) reflects a partial difference. This implies that, at this stage of introducing SNS as a means of enhancing public relations, that aggressive SNS usage by the professional conference organizer (PCO) and the convention organizer is encouraged as means of preempting positive event affection. This study has meaningfulness in enhancing academic value of the convention study by applying the concept of organization-public relationship which has been positioned as an important concept at PR to the convention study.