This essay examines the process of Japanese exclusion from commercial fishing in Hawai'i before the end of the Pacific War. As the U.S.-Japan relations deteriorated after the late 1930s, the federal government and the U.S. Navy heightened their suspicion that Japanese fishermen were acting for the expanding Japanese empire and imposed various regulations on fishing operations. After the Pearl Harbor attack, the Office of the Military Governor in Hawai'i banned fishing and excluded Japanese from Hawaiian waters. In the meantime, local fisheries agencies worked for the reconstruction of fishing. Through negotiations with the Office of the Military Governor, they promoted deregulation of fishing activities and paved the way for the post-war prosperity of Japanese fishing in Hawai'i.