Previous studies have examined the relationship between job security and knowledge sharing behavior, often use job security as a moderator, however, through previous studies, job security may be a trigger knowledge sharing behavior. In addition, gender may have a moderating effect on that relationship. Therefore, the purpose of this study is to investigate the relationship of job security and gender to knowled sharing behavior. Using survey questionnairs, the sample included 324 employees in 4 Taiwan accounting firms. Hierarchical regression analysis was used for data analysis. Empirical data showed that job sectury to be positively related to knowledge sharing behavior. However, the moderating effect of gender was not supported. Theoretical and practical suggestions are also provided.