This article reconsiders prevailing assumptions of bureaucratic continuity in postwar Japan by examining the case of the Ministry of Communications during the Allied Occupation. While existing scholarship emphasizes institutional inertia, this study shows how structural reform and inter-institutional negotiations involving both American authority and Japanese agency reshaped parts of Japan’s administrative system. The case calls for a more differentiated, organization-focused perspective on postwar reforms and demonstrates that these transformations had enduring effects beyond 1952.