The Korean Constitutional Court(KCC) was created as a result of democratization in 1987. Scholarly works that explain its institutional origin and formation process are rare. One of the existing explanations is Ginsburg’s insurance theory, which emphasizes actors’ rational-strategic choices under the condition of political uncertainty. However, this has a number of problems in terms of both historical facts and logical consistency. Employing critical juncture theory, this paper aims to provide an alternative theory-informed explanation of KCC’s institutional formation. Corresponding with that theory, the major features of the KCC were determined by the combining effects of contingency and political key actors’ decision in 1987. Since its establishment, KCC has showed an unexpected development. The explanation by Critical Juncture theory of the KCC suggests that we should alert to the limit of rational-strategic choice approaches and the importance of context in analytic and practical terms.