Psychologists and researchers of management sciences are of great interest in subject of stress and the major reason for this is its impact on psychological well-being and organizational consequences. They also recommend that preventing stress called destructive stress results from factors such as role ambiguity, role uncertainty, and organizational policies, and decreases both the individual and organizational performance. The purpose of this study is to investigate the effect of role conflict and role ambiguity on employees' job stress by explaining the role of work-family conflict. The statistical population of this study is comprised of 530 employees of Iran's central insurance. Using stratified random sampling and Cochran's formula, a sample of 118 employees was selected. We used a researcher-made questionnaire for data gathering. The Cronbach's alpha for this questionnaire was .88 and split-half reliability was .80, which represents for a reliable questionnaire. Furthermore, we used content validity and confirmatory factor analysis to confirm the validity of questionnaire. Data analysis was accomplished by structural equation modeling using the LISREL software v 8.7. Research results indicate that the effect of role ambiguity on work-family conflict is statistically significant (p-value = 62.40). Furthermore, the effect of role ambiguity on job stress was confirmed with significance of 1.83. On the other hand, the effect of role conflict on work-family conflict was not confirmed, because its significance value was negative. However, it was found that the job stress is influenced by role conflict (p-value = 2.35). And finally, the effect of work-family conflict on job stress was confirmed with the number of .93 for its significance value.