This study reviewed the current state of the footnote disclosure system for related party transactions and empirically analyzed the effects of related party transaction volume and firm characteristic factors on the related disclosure level. Given that managerial discretion is likely to be involved due to the nature of related party transactions, footnote disclosures on firms' related party transactions should specify detailed transaction details to provide useful accounting information to external investors. However, it has been pointed out as a problem that the absence of clear regulations regarding related party transaction disclosures has led to differences in footnote disclosure methods across firms. If such discretionary accounting choices through disclosure levels become possible for individual firms, incentives to provide only information favorable to the disclosing entity will arise, thereby reducing the transparency of accounting information and inter-firm comparability. Furthermore, if information about large-scale transactions requiring monitoring and control for impropriety is concealed, information asymmetry with external stakeholders will intensify, necessitating regulation and institutional supplementation for appropriate disclosure levels. Therefore, this study verified the characteristics and determinants of firms that affect differential disclosure levels, focusing on disclosure forms that conceal specific information related to related party transactions. The analysis results showed that the larger the related party transaction amount, the lower the footnote disclosure level. Meanwhile, when related party transaction amounts were classified according to profit-and-loss criteria, it was found that disclosure levels decreased only when firms realized profits through transactions (propping). Finally, the analysis of differences in the relationship between related party transaction volume and disclosure levels according to membership in large business groups revealed that significant correlations existed only for firms not belonging to large business groups, to which additional government regulatory policies on related party transactions are not separately applied. Consequently, it was observed that firms not belonging to large business groups or firms that realize favorable profits through related party transactions are more likely to choose arbitrary pattern changes in their related disclosure forms. Therefore, to resolve information asymmetry in the market and improve the quality of accounting information, firms' active disclosure efforts regarding information disclosure, as well as discussion of institutional supplementation by supervisory authorities to induce appropriate disclosure levels, should be undertaken.