This paper is a research on perceived risk of social commerce which has influence on purchase intention. This study uses a 3-dimension concept of perceived risk and then, deals with influencing a purchase intention. In addition, to search other influential variable to purchase intention, this study adds a variable with expected moderating effect. This study proposes several hypothesis and processes an experiment to test and attest these hypothesis. This study attempts to analyze the effect that perceived risk in social commerce has on purchase intention. By the results of data analysis, all dimensions of perceived risk are found to have significant negative effects on purchase intention. In addition, this study proves moderating roles of valence of WOM Information on purchase intention. Additional managerial implications are also discussed.