This study focuses on the Japanese perception of the sovereignty of Dokdo, focusing on the affidavit of a case where Japanese merchants and officials of the Hamadaclan were punished for illegally invading Ulleungdo in 1836. Through an analysis of this case, we can see that the Japanese claims of sovereignty over Dokdo which are currently based upon this case are precarious. In the years between 1833 and 1834 merchants from the Hamada region of Japan were making profits by logging in Ulleungdo, the Japanese government judged this as illegal and through the Hachiemon, punished them for profiting from it. The Japanese merchants who invaded Korea's territory on Ulleungdo, illegally plundered timber and seafood and on two occasions were themselves charged with illegal acts that violated Japanese domestic laws. The actions of the Hamadaclan officials who tolerated or aided their illegal activities were of the Edo Shogunate. This was an illegal act that violated the prohibition of this case. Even the former lord of the Hamadaclan was punished for failing to properly manage and supervise his residents and vassals. It was an incident that shocked Japanese high society at the time. However, Japan currently argues that it was not illegal to cross into Dokdo based upon Hachiemon's statement, and is using it as a basis for claims of sovereignty over Dokdo. Through this study, it is clear that the judgment at the time did not tolerate crossing into Dokdo as a legitimate act. Instead, it clearly proves that Ulleungdo and Dokdo were recognized as Korean territory. This study makes it clear that this perception had already been formed in the late 17th century. Therefore, Japan's claim based on the statements made by Hachiemon's party (who was punished under Japanese domestic law), is only a compelling claim and it has lost its legitimate basis, therefore Japan's claim upon Dokdo's sovereignty should be denied.