The purpose of this study was to examine major motivations for using SNSs and the effect of them on SNS participation. In order to address the research questions, 253 undergraduate and graduate students participated. Results of the study were summarized as follows. First, Cyworld was mainly used followed by Facebook and Twitter. Most of the respondents had access to SNSs via smart devices. The average frequency of SNS use was 1-3 times a day and they used them less than 30 minutes a time. The reasons why they started to use SNSs were mainly to follow current trends, maintain friendship, and accept acquaintances recommendations. Second, the result of component analysis derived four primarily underlying dimensions related to SNS use; self-satisfaction, social interaction, recreation, and information seeking. Third, both self-satisfaction and social interaction motivation had significant correlation with SNS participation. The results of multiple regression analysis showed that self motivation was more influential on active participation than social interaction and information seeking motivation.