本研究檢驗關於企業社會責任與公司債務資金成本之間關聯性 （以信用評等作為代理變數）的兩個問題。第一、我們檢驗公司承 擔社會責任是否對於信用評等具有增進的作用，並因此減少了公司 的債務資金成本。第二、我們考慮並檢驗信用評等是否可作為企業 社會責任和公司的盈利能力之間的中介。這裡的中介是指，當信用 評等存在於迴歸式中時，相對於不存在時，企業社會責任對公司績 效的影響較不明顯。根據2005 年至2009 年期間之台灣證券交易所 上市公司的資料，實證結果顯示，承擔企業社會責任的公司往往有 較佳的信用評等，也因此有較低的債務資金成本；此外，在控制信 用評等後，社會責任對公司盈利能力的影響降低，從而顯示信用評 等可作為企業社會責任和公司獲利之間的中介。

This study examines two issues related to corporate social responsibility (CSR) and the firm’s cost of debt as, proxied by credit ratings. First, we investigate whether CSR has a positive effect on credit ratings and therefore reduces the cost of debt. Second, we consider the credit ratings as the mediator between CSR and the firm’s profitability. The mediator here means that, given the presence of credit ratings, the impacts of CSR on the firm’s performance will be lower than in those cases where credit ratings are not considered in the regression analysis. By employing companies listed on the Taiwan Stock Exchange (TWSE) during 2005~2009, our results show that CSR firms tend to have higher creditworthiness and therefore a lower cost of debt. In addition, after controlling for credit ratings, the impact of CSR on the firm’s profitability is reduced, thereby showing that credit ratings serve as the mediator between CSR and performance.