This study aims to explore the influence of Korean middle school students participation in extra-curricular activity on their citizenship. Utilizing responses of 4,887 second-year middle school students included in the 5th(2016) year of the Gyeonggi Education Panel Study, descriptive statistics, correlation analysis and multiple regression analysis were conducted. The result shows that students participation level in extra-curricular activity was not high, in particular, in student council activities, volunteer activities and reading activities. The level of citizenship of students, on the other hand, was generally high, marking higher level in openness and law-abidingness. Second, students extra-curricular activity, the independent variable, had a statistically significant impact on the citizenship, the dependent variable, and the magnitude of the impact was in the order of career activities, reading activities, volunteer activities and student council activities. The result of study confirms the possibility that students citizenship can be promoted by extra-curricular activities organized by the schools. Based on the findings, we suggested policy recommendation to improve middle school students extra-curricular activities qualitatively as well as quantitatively.