本研究檢視供應鏈會計師對裁決性應計數之影響。由於供應鏈會計師同時具備供應鏈關係中上、下游受查客戶之財務資訊，不僅擁有豐富經驗與查核技巧，亦能靈活運用查核所得之進貨、銷貨資訊輔助驗證真實銷貨與進貨狀況，據此，本研究認為聘任供應鏈會計師能降低裁決性應計數。本研究更進一步將供應鏈會計師區分為上游供應鏈會計師與下游供應鏈會計師，分別以兩者擁有的不同資訊來分析其對裁決性應計數之個別影響。實證結果顯示，聘任供應鏈會計師的確能顯著降低裁決性應計數之使用幅度，而下游與上游供應鏈會計師亦能分別抑制管理階層使用正向與負向裁決性應計數。另外，本研究以首次聘請供應鏈會計師樣本發現，供應鏈會計師較能降低裁決性應計數，而下游供應鏈會計師較上游供應鏈會計師更能對裁決性應計數之絕對值產生負向影響。 This paper examines the effect of auditors' supply chain expertise on discretionary accruals of major suppliers or customers in supply chain relationships. With sufficient industry knowledge and experience, a supply chain specialist auditor can provide quality-differentiated audit services by integrating financial information of supply chain partners. Therefore, this paper infers that supply chain specialist auditors enhance audit quality by decreasing the usage of discretionary accruals for their understanding of real purchase and sales transactions. This paper further categorizes supply chain specialist auditors into downstream and upstream specialist auditors considering the differences in their acquired financial information. Results indicate that supply chain specialist auditors decrease the magnitude of discretionary accruals. Moreover, positive and negative discretionary accruals decrease by employing downstream and upstream specialist auditors, respectively. Furthermore, this paper provides evidence that the cross-period discretionary accrual changes are made more by downstream specialist auditors than upstream when supply chain partners hire a supply chain specialist auditor for the first time.