The purpose of this study was to examine the relationship between internal auditor's self-efficacy and internal audit quality. Role overload are introduced to examine the moderator effect on internal auditor's self-efficacy and quality. Three hundred and ninety anonymous surveys from publicly traded company's internal auditors in Taiwan was analyzed to examine the research problem. Results indicated that internal auditor's self-efficacy was related to internal audit quality and three dimensions. Also, we found that the relationship between internal auditor's self-efficacy and internal audit quality was moderated by the internal auditor's role overload. Further research and practical implications of these findings are discussed.