A B S T R A C TThe purpose of this study is to investigate the impact of job demand on employees' social network service addiction and how it influences their job satisfaction and organizational citizenship behavior. And we explore if occupational self-efficacy can moderate the relationship between job demand and social network service addiction. In the results, first, job demand increases social network service addiction. Second, social network service addiction decreases job satisfaction and organizational citizen behavior. Finally, employees' occupational self-efficacy decrease the effect of job demand social network service addiction. (Wilson, et al., 2010). SNSs are predominantly used for social purposes, mostly related to the maintenance of established offline networks, relative to individual ones (Kuss & Griffiths, 2011). However, recent evidence suggests that individuals may feel compelled to maintain their online social networks in a way that may, in some circumstances, lead to using SNSs excessively.Existing body of researches have various three † Youngkeun Choi