OBJECTIVES: In South Korea, many individuals were self-quarantined for the coronavirus disease 2019 (COVID-19) after the quarantine criteria were extended to all overseas travelers. This study was conducted to identify the noncompliance rate of self-quarantine for COVID-19 cases and assess the impact of a 1-strike out policy and an increased amount of penalty for the violating self-quarantine in South Korea. METHODS: The self-quarantine noncompliance rate for COVID-19 was examined using publicly available data. We collected the daily number of quarantine and quarantine violation cases from March 22 to June 10, 2020. A Poisson regression analysis was conducted to identify the impact of additional sanctions for the quarantine violation. RESULTS: The median number of individuals quarantined per day was 36,561 (interquartile range, 34,408-41,961). The median number of daily self-quarantine violations was 6 (range, 0-13). The median rate of self-quarantine violations was 1.6 per 10,000 self-quarantined individuals (range, 0.0-8.0 per 10,000 self-quarantined individuals). The additional sanction has no significant impact on the number of violations among quarantine individuals (P = 0.99). CONCLUSIONS: The additional sanction for the violation of quarantined individuals did not reduce the self-quarantine violations. Further studies are warranted to strengthen the compliance of self-quarantine for future pandemics.