Disclosure of patient safety incidents (DPSIs) is a strategic measure to reduce the problems of patient safety incidents (PSIs). However, there are currently limited studies on the effects of DPSIs on resolving diagnosis-related PSIs. Therefore, this study aimed to estimate the effects of DPSIs using hypothetical cases, particularly in diagnosis-related PSIs. A survey using 2 hypothetical cases of diagnosis-related PSIs was conducted in 5 districts of Ulsan Metropolitan City, Korea, from March 18 to 21, 2021. The survey used a multistage stratified quota sampling method to recruit participants. Multiple logistic regression and linear regression analyses were performed to determine the effectiveness of DPSIs in hypothetical cases. The outcomes were the judgment of a situation as a medical error, willingness to revisit and recommend the hypothetical physician, intention to file a medical lawsuit and commence criminal proceedings against the physicians, trust score of the involved physicians, and expected amount of compensation. In total, 620 respondents, recruited based on age, sex, and region, completed the survey. The mean age was 47.6 (standard deviation, ±15.1) years. Multiple logistic regression showed that DPSIs significantly decreased the judgment of a situation as a medical error (odds ratio [OR], 0.44; 95% confidence interval [CI], 0.24-0.79), intention to file a lawsuit (OR, 0.53; 95% CI, 0.42-0.66), and commence criminal proceedings (OR, 0.43; 95% CI, 0.34-0.55). It also increased the willingness to revisit (OR, 3.28; 95% CI, 2.37-4.55) and recommend the physician (OR, 8.21; 95% CI, 4.05-16.66). Meanwhile, the multiple linear regression demonstrated that DPSIs had a significantly positive association with the trust score of the physician (unstandardized coefficient, 1.22; 95% CI, 1.03-1.41) and a significantly negative association with the expected amount of compensation (unstandardized coefficient, -0.18; 95% CI, -0.29 to -0.06). DPSIs reduces the possibility of judging the hypothetical case as a medical error, increases the willingness to revisit and recommend the physician involved in the case, and decreases the intent to file a lawsuit and commence a criminal proceeding. Although this study implemented hypothetical cases, the results are expected to serve as empirical evidence to apply DPSIs extensively in the clinical field.