Objectives This study aimed to identify factors related to medication errors in hospitals, provide basic data for medication safety, and to provide evidence to develop an intervention program to prevent medication errors. Methods This cross-sectional descriptive study was using the 2021 patient safety report data released by Korea Institute for Healthcare Accreditation. Of the total of 13,146 patient safety incidents, 4,198 medication errors were used, excluding psychiatric hospitals, oriental medicine hospital, and missing data were excluded. Descriptive statistics, Chi-square test, and multinominal logistic analysis were performed using SPSS 26.0 program. Results Factors affecting adverse events of medication errors were age, the place of occurrence and bed size. In addition, the factors influencing the sentinel event of medication error were the evening shift, the place of occurrence. Among the medication errors 70.4% (1,201) were near misses, 26.1%(445) were adverse events, and 3.5% (59) were sentinel events. Conclusions In order to prevent medication errors in medical institutions, factors that can affect medication errors by work department should be identified in various aspects, such as organizational, management, system, and human factors, and sufficient medical personnel, positive working environment, and medication safety system should be improved.