隨著 ESG 議題受重視，工作場所安全已成為企業永續經營的關鍵。本研究探討外部客戶結構對供應商非財務績效之影響，採用 2002 至 2011 年美國大型公司樣本，結合 OSHA 工傷紀錄與 Compustat 財務數據進行實證分析。 研究結果顯示，客戶集中度與供應商總工傷率（TCR）、InjuryEmp及Num_case呈顯著負相關，支持「監督機制假說」。透過「建立主要客戶關係」之準自然實驗與雙重差分法（DiD）檢驗，證實主要客戶扮演「非官方監管者」角色，能有效促使供應商改善安全管理。機制分析顯示，此正面效應僅在融資受限較輕且公司治理品質較佳的企業中顯著，說明充足的財務資源與健全的內部制衡是落實外部監督要求的必要條件。本研究深化了對供應鏈治理與內外部治理互補效應之理解，對監管機關與大客戶推動供應鏈永續發展具有政策意涵。;This study examines the impact of customer concentration on a supplier’s workplace safety using a sample of large US firms from 2002 to 2011. By integrating OSHA injury rec-ords with Compustat financial data， we find a significant negative correlation between cus-tomer concentration and a supplier’s TCR ， InjuryEmp， and Num_case. Utilizing a Differ-ence-in-Differences (DiD) approach based on the establishment of major customer relation-ships， the results support the "Monitoring Mechanism Hypothesis，" suggesting that major cus-tomers act as "unofficial monitors" to drive safety improvements. Mechanism analyses reveal that this positive spillover effect is only significant in firms with low financing constraints and high corporate governance quality. These findings indicate that financial flexibility and internal oversight are essential prerequisites for translating exter-nal monitoring into actual safety performance. This research provides critical insights for reg-ulators and major firms seeking to enhance supply chain sustainability through collaborative governance.
