The purpose of this paper is to analyze the wartime transportation control of Japanese National Railways (JNR) and make it clear that the management of JNR reached the limit, as the lack of JNR's management resources and U.S. Air Force's raid became intense.<br>Since the Sino-Japanese War broke out, JNR had to cope with the sharply increased transportation demand caused by the industrial development as well as the military operation. In addition to the demand increase, JNR was always requested to supervise and support other companies, especially colonial railways as not only a transportation enterprise but also a regulatory agency to transportation companies. However, JNR was not a passive existence but the one to secure human and physical resources aggressively to some degree in case of negotiations with other ministries as one of the government ministries. As far as the railroad operation was possible, the profit seeking was a subsidiary matter. The persistent cooperation of JNR with Japanese Government and Army was shown by maximum transportation capacity even when JNR had insufficient management resources. Especially, after the breakout of WWII, Japanese wartime economic management could be difficult without the land transportation of JNR which substituted for marine transportation. Nonetheless, JNR resisted Japanese Army's intention to seize the railroad management right, which led to the dissatisfaction of the Army until the end of war.<br>As a result, an efficient railroad operation system was accomplished according to the evolution of wartime economy and military situation. But, it reached the limit because of the lack of JNR's management resources and U.S. Air Force's raid.