This study examines the theory and practice of direct democracy which lacks in-depth understanding and comparative study. The main arguments and major findings of this study are summarized as follows. First, the widest and oldest misconceptions associated with direct democracy are the criticism that it can contradict popular democracy and add to the instability of the system. The main argument is that the expansion of direct democracy at the national level is likely to conflict with parliamentary system or political party politics. However, the objection to this is also increasing in quantity and quality, and the point is that the relationship between the two is not a contradiction or substitute, but a virtuous circle of mutual complement. Advocates argue that, above all, direct democracy promotes the development of political parties as well as the government by activating communication and cooperation between politicians and voters. Switzerland and the United States are typical examples of this claim. Second, we examined the international situation of direct democracy from the point of view of comparison by country. This study confirms that direct democracy has surged over the past 30 years at the national and local levels. The characteristics of each type are as follows: First, the bottom-up referendum, which is prescribed by the Constitution or suggested by the people, has increased significantly, rather than the top-down referendum that the government, especially authoritarian or dictatorship, has imposed from above. Second, citizen initiated votes did not increase as much as we expected. Third, the recall rate was the lowest among the three systems. Third, in view of the global trend, the introduction of direct democracy in Korea should be based on the so-called "expansionism based on constitutionalism", which adopts the provisions stipulated in the Constitution (the law) and adopts the referendum, the national initiative and recall, respectively.