The East Sea (or Sea of Japan) (ESR/SOJ) Rim region, in which five countries – Japan, China, Russia, and North and South Korea – have their own coastal areas, is complex and dynamic, with many emerging regional security concerns. In this paper, the author tries to show that there is the possibility of a maritime regional regime in the ESR/SOJ region by investigating the level of public support, in Japan and South Korea, for the formation of a regional regime. Based on the theoretical assumptions of constructivism, the author analyzes what kinds of individual's social position factors influence the level of support for regional regime formation by conducting a nested regression model of survey datasets. The results of the statistical analysis suggest that people with a high level of national pride in South Korea are more likely to support a regional regime in the ESR/SOJ region. In contrast, for Japanese people, there is no relationship between people's national pride and the level of support for regional regime formation. The economic recession in Japan since the early 1990s has made public concern more about domestic policy than about foreign policy issues. Based on strong support of the bottom, public opinion towards regional regime formation, the South Korean government may play a leading role in developing a regional regime in the ESR/SOJ region (when the process of negotiation begins) as in the case of Japan in nineteenth century.