The purpose of this study is to shed light on the driving motivations of contributing social word of mouth on social networking sites (sWOM) toward both tangible and intangible products. In order to develop a research model, this study adopts the motivation theory and TAM model. Data was collected from 904 members of the cosmetic and restaurant communities by using the snowball method. After assessing the validity of all constructs, the structural equation modeling (SEM) is used to test the proposed hypotheses. Results show that personal motivations (satisfaction, opinion leadership, self-enhancement, and economic incentives) and characteristics of sWOM (Perceived Usefulness and Ease of Use) have positive effect on exposure and engagement behaviors. Here are our specific findings, (1) customer satisfaction positively affects online interactions on SNSs such as Like or Sharing a content; (2) sWOM contribution behavior exists in two structures (Exposure and Engagement) and affects each other; (3) This study combines two groups of personal motivation and TAM to conceptualize a research model; and (4) The motivations of contributing sWOM between a specified service and product are rather similar. These findings help digital managers to understand consumers' behavioral contributions on SNSs and also provide interesting insights for marketers.