The purpose of this study is to investigate the impacts of two different kinds of interactivity, such as user-to-user and user-to-media interaction, on the relationship between SNS motivation and online word of mouth (WOM). An online survey was conducted with SNS users in Korea. Using the convenience-sampling method, 300 surveys were collected and 295 were used in the actual analysis after excluding data with careless responses or missing values. Hypotheses were tested using Structure Equation Model (SEM) and path analysis by using AMOS22. The results indicate that four different SNS motivations (self-expression, relational, fun, and browsing motivation) have a partially significant positive effect on perceived user-to-user and user-to-media interaction in SNS. Although both user-to-user interactivity and user-to-media interactivity were found to have a significant effect on online word of mouth, by comparing the standardized regression coefficients in these relationships, it was found that user-to-user interactivity has a greater effect on online WOM than user-tomedia interactivity. These results show that the motivated SNS users want to express their desire to communicate with other users in contrast than their desire to learn media functions when motivated SNS users reveal their personalities, knowledge, and abilities. Theoretical and managerial implications are discussed.