Background: Regional disparity is an imperative component of health disparity. In particular, providing emergency care that is equally available in rural areas is an essential part of reducing the urban–rural disparity. The objective of this study was to examine the worsening admission rate among Cambodian emergency patients in a rural area and determine their background characteristics that cause this decline. Methods: To investigate the disparity among patients who visited Sunrise Japan Hospital (SJH), a major general private hospital in the capital, patient data from November 2016 to September 2019 were obtained from the electronic reception patient database. The primary outcome was defined as the proportion of admission patients as an indicator of illness severity. The patients’ addresses were classified into 4 areas based on distance from the capital. Results: A total of 6167 patients who visited the emergency department at SJH between January 2017 and September 2019 were included in the analysis. The proportion of patients who needed to be hospitalized or transferred increased with the distance from the capital. The proportion of patients who finished consultation decreased with the distance from the capital (P<.01: Chi-square test). The results of the logistic regression analysis showed that the admission rate in rural areas was significantly higher only among males as compared to that of the capital in multivariate analyses adjusted for age, time, and season. Conclusion: The admission rate of emergency patients who visited a private general hospital in Cambodia’s capital city increased with distance from the capital city. To improve regional disparity among emergency patients, further research is necessary to identify the issues among emergency patients, especially those who are vulnerable.