In the analysis of the particular commercial firm like company, bank and so forth, it is necessary to use the first hand documents such as account books or diaries, so that we can penetrate into their real activity or inner structure in their totalty. Such way of analysis has been frequently used in the cases in Japanese and Western economic history. This is also true with cases of Chinese economic history. This paper tries to show the activities of the Sheng-Tai Hao (生泰号) Company in Nagasaki, by way of the author's detailed research into the account books it possessed, in the hope of filling the gap which has been studied so little. The founder of the Sheng-Tai Hao was a merchant who lived in the last days of the late Ch'ing period and came over to Nagasaki from Fu-chou of Fu-Kien province. Nagasaki has been a sole trading port opened for the sea-trade between China and Japan since the early Tokugawa era. With the opening of that port as one of treaty-ports in 1858, the Chinese merchants had to dwell in the quarters assigned as foreign residence, at that time, the Sheng-Tai Hao establishd its firm im Shinchi-cho within that quarters and remained to stay there until 1948. After the Second World War it changed its business and became a Chinese restaurant. The Sheng-Tai Hao was a firm owned and operated by the Chen family, slong with their relatives and the persons recruited from their hometowns who amounted to about twenty members in all. The Sheng-Tai Hao was a whole-sale dealer, dealing the import of goods from China such as silk, furniture, writing brush, cosmetics, etc. and export of marine-products. In addition, it dealt retail business only partially (about 20% in the sales). The sphere of its business spread very extensively; from Kyushu to Tokyo, Shang-hai, Taiwan, Korea, having had about 970 customers at its heyday. Its gross annual sales of about 90,000 yen plus annual profits of about 20,000 yen which could be ranked as a middle scale firm among the Chinese companies therein. Only a part of the books possessed originally by the Sheng-Tai Hao, nevertheless, the eighteen different kinds of books extant which compose a series of documents ranging from daily records to ledgers of the main and the subsidiary books, are of particular importance. Generally, the Sheng-Tai Hao books could be defined as those compiled by the single entry book keeping method. Its mode of book keeping also could be grouped into such localized one as that prevailed in Amoy area in Southern Fukien. It should be noted that it was kept without any influence from western double entry book keeping technique. The books can be devided into two kinds in size: the larger one, 24 cm by 18.5 cm, and the smaller one, 15 cm by 22 cm. Every entry was writtern by Chinese brush and by use of Shuchou numerals. A line in the midde divides the space into two parts, the upper shows Debtor and the under shows Creditor. All in all, this management and book keeping method should be regarded as a typical example of the old-style Chinese trading companies.