Port and harbour was the first place where a person encounters someone else who has a different background. In the middle of the nineteenth century, the Japanese government abolished its so-called closed-door policy and started trading with foreign countries. One of the biggest issues in the negotiations between Japan and western powers was who and how governed the brand-new opened port towns. In contrast to the cases of Chinese open ports, the self-governing body of the foreign settlements in Japan did not last. Therefore, regulations which were issued by both Japanese governments and foreign representatives were the bases of administrations in these towns. This paper aims to examine what kind of regulations were needed and how they went through changes in Japan's open ports, particularly in the earliest stages.