This article studies the mechanism of sonno joi ("Revere the Emperor, Expel the Barbarians"), which caused the dissolvement of bakuhan system and consequently brought about Meiji Restoration. Sonno joi, originally means crying for the expulsion of western powers, came to consent to kaikoku (opening ports) and accept westernization, displaying great changeability in logic and goal as Japan`s foreign and domestic political situation developed. The uncertainty of the logic of sonno joi stems from the basic fragility of the dual political structure of the bakuhan system, in which the shogun, as a practical executioner of political power, and the tenno, a symbolic authority with little power, coexisted. The Bakufu`s ambiguous political ground never allowed Japan to have a sound national ideology like Korea. The absence of a value system that was strong enough for ideological control led to the rise of kokugaku and its impact on sonno joi.