This research focuses on the disclosure patterns of related-party transactions and analyzes the relationship between these transactions and characteristics of companies in terms of disclosure. Because managers often exercise their discretionary powers through related-party transactions, disclosure of these transactions may include useful information for external investors in the form of specific transaction details. However, because the current accounting standards are unclear regarding footnote disclosures in reports containing information about related-party transactions, many users of accounting information have identified differences in disclosure methods in between individual firms. If discretionary accounting choices are allowed, then some managers may disclose only good news favorable to themselves; thus, the transparency and comparability of accounting information will deteriorate. In such cases, it is necessary to monitor and control large transactions between related parties to prevent corrupt practices. However, when this transaction information is arbitrarily hidden, this lack of disclosure increases information asymmetry among interested parties. This study focuses on disclosure patterns and hidden actions that conceal specific information about related-party transactions. We analyze firms’ corporate characteristics and identify factors affecting disclosure about related-party transactions. The empirical findings are as follows. First, we find that disclosure(footnote) quality decreases as the trade volume of related-party transactions increases. Second, in cases of propping, we confirm a significant decrease in the number of disclosures of related-party transactions. Lastly, according to the results of an analysis on differences in disclosure behavior by business groups, a decrease in disclosure associated with related-party transactions is observed in non-large business groups. In conclusion, firms that belong to large business groups and those that engage in propping tend to change their patterns of disclosure according to the manager’s discretionary decision-making. Therefore, in order to reduce information asymmetry in the stock market and improve the quality of accounting information, supervisory authorities must discuss institutional regulations to ensure adequate disclosure levels(quality) and encourage active disclosure. Most former research studies develop their arguments assuming that the nature of transactions causes information asymmetry while ignoring the loophole in the disclosure system of relatedparty transactions. Also, considering that studies on the disclosure standards associated with related-party transactions and the factors influencing disclosure are practically non-existent, this paper provides valuable information about related-party transactions and how the disclosure system fails to address issues related to them. By examining these issues, suggest that the problems related to the market’s biased perception of related-party transactions and the limitations of the information environment can be alleviated by taking complementary measures to improve disclosure standards. Furthermore, while discussion is ongoing about establishment of an effective monitoring system to prevent managers’ opportunistic decisionmaking during disclosure of related-party transactions, this thesis provides a suggested configuration and theoretical implications on the direction of future regulatory policy and oversight of relatedparty transactions through revision of the involved disclosure system.