SNS is getting its popularity as a channel for building a long-term relationship with customers and generating online consumer word-of-mouth. This study is designed to examine factors influencing online sharing activities that generate consumer word-of-mouth. TPB (Theory of Planned Behavior) is used to predict online sharing intention and the theory is expanded by adding three other explaining variables (perceived self-expression, expected positive emotion and expected loneliness) and one moderating variable (consumer's social capital). The results of online survey indicated that sharing intention was influenced by subjective norm, perceived behavioral control, perceived self-expression, and expected positive emotion. Moderating effects of social capital showed that attitude, perceived behavioral control, and expected positive emotion were the key factors explaining sharing intention for bridging social capital while perceived behavioral control and expected loneliness were the important predictors of sharing intention for bonding social capital. In addition, people with bridging social capital tend to use 'like' function more while bonding people used more tagging function. Implications of study findings are provided for strategic use of consumer word-of-mouth for advertisers' viral campaigns.