明政權成立後，因恐佔據沿海島嶼的反明勢力，以及元末以來橫行於朝鮮半島和 中國沿海的倭寇侵擾，而實行海禁政策。倭亂平後，雖因應國內外情勢，於 1567 年部份開 放海禁，但依舊嚴禁赴日貿易。為獲取貿易巨利，特別是日本銀，走私貿易盛行；加上日本 各地對中國物產如絲、綢緞類之需求，地方之有力者及高官亦獎勵貿易，因此，即使在海禁 下，兩國間貿易船往來頻繁，居留於日本者日多。這些居留日本中國人的構成有：遭倭寇擄 掠而來者；走私貿易商人或流逋、無賴之徒；明末清初中國國內內亂，加上明清鼎革，避難 赴日者。其後，因日本實施「鎖國」政策，貿易限制在長崎一港，各地居留中國人也集中於 長崎，華僑社會因而形成。本文主要在分析，明末海禁下中日走私貿易的實態，及日本發佈 「鎖國令」之重要內容，和其與長崎華僑社會形成的關係及華僑社會的變遷問題。

　　　　　After the building of the Ming dynasty, the Ming government took its ban policy on maritime trade in order to prevent intrusions from the anti-Ming forces who had occupied islands near China's coastal areas as well as the Japanese pirates who invaded Korean Peninsula and China's coastal regions. Although the Ming government modified its ban policy and opened maritime trade only partly in 1567, after the Japanese pirates had been pacified, the Sino-Japanese trade was still banished. In order to get big profit, particularly Japan's silver, smuggling trade with Japan was very popular. In additional, under the influence of the demand of China's silk goods for the Japan's market, Japanese local leaders and high officials encourged their people to trade with Chinese merchants. Therefore, even the banishment of the ban policy still existed, trade ships visited Japan very often and the amount of overseas Chinese in Japan increased gradually. Those overseas Chinese who residented in Japan consisted of the kidnapped by the Japanese pirates, smuggling merchants, and the banished and rogues. Because the internal riots occurred during the late Ming and early Ch'ing era, and the Ch'ing replaced the Ming as a new dynasty, thus, the Chinese emigranted to Japan for safety. After the trade between China and Japan was limited to the area of Nagasaki port since the Japanese government took its National Seclusion Policy, the overseas Chinese moved to Nagasaki and established finally their own community in Japan.