環境（Environment，簡稱E）、社會（Social，簡稱S）及公司治理（Governance，簡稱G）被提出後，全球各國企業的利害關係人都逐漸開始重視企業是否有落實ESG的議題。而債權人在放款時，除了會透過信用評等來評估企業風險外，還會將企業落實ESG的相關資訊納入其決策過程。本研究以2014年至2021年期間的臺灣上市櫃公司為樣本，探討企業的永續報告書與第三方確信是否會影響債務資金成本；並進一步檢視企業的負面社會責任新聞的干擾效果。實證結果發現，企業出具永續報告書及有經第三方確信，皆有助於降低債務資金成本，但當企業發生負面的社會責任新聞時，反而產生反效果，顯示永續報告書及第三方確信報告是債權人形成放款決策過程中的重要參考資訊。為提升永續報告公信力，強化企業的風險管理及公司治理機制，本研究實證結果支持政府持續推動與規範企業永續報告揭露與第三方確信之相關決策與作為。

Stakeholders are increasingly interested in ESG (Environment, Social, and Governance) issues, while ESG reporting can help stakeholders assess risks and business performance in a company. We take Taiwan-listed companies from 2014 to 2021 as samples to explore whether sustainability reporting and external assurance can influence the cost of debt. Further, how the media coverage of negative social responsibility news moderates the relationship between sustainability reporting and the cost of debt is investigated. Our empirical results indicate that the cost of debt for firms that issue sustainability reports with external assurance is lower than others, which may be associated with the reduction of information asymmetry between a firm and its stakeholders. However, the media coverage of negative social responsibility news will increase the cost of debt, suggesting that negative social responsibility news matters to creditors. Overall, our findings stress the importance of companies issuing sustainability reports and external assurance.