Purpose ? This study verifies whether the effect of ETS(Emissions Trading Scheme) on debt financing costs is differentiated according to the export concentration, Also, this study verifies whether the increase and decrease effects of debt financing costs according to the characteristics of ETS companies are differentiated according to the export concentration. Design/Methodology/Approach ? This study analyzes companies listed on the Kore Exchange, and the analysis period is from 2015 to 2020 since the emission trading scheme started in 2015. Findings ? The results of the analysis are as follows. First, in companies with no exports and low exports concentration, debt financing costs are reduced due to the ETS. Second, when the carbon intensity is high in a company with high export concentration, the increase in debt financing cost is larger. Third, when the energy efficiency is high in companies with no exports and high export concentration, decrease in debt financing cost is larger. It can be seen that debtholders are differentially aware of the effect of the ETS according to the degree of export concentration, and consider the degree of export concentration even when considering the characteristics of companies responding to the ETS. Research Implications ? The results of this study will be helpful for corporate strategies and governments’ support policies for ETS firms. In addition, it will provide practical implications for capital market participants who evaluate climate-related risks.