The German historian Dr.Ludwig Riess (1861-1928) is widely recognized both in Japan and Europe. In Europe, he is still known as the author of "Die Weltgeschichte," and other works, while in Japan he is mainly known as one of young foreign advisors employed by the University of Tokyo during its formative years (1887-1902). This article attempts to clarify those years in Japan by focusing upon Riess' efforts to introduce European archival materials relevant to the study of Japanese history. 1.During the second year of Riess' employment, University President Koki Watanabe 渡辺洪基 sought his advise concerning the question of how to open and operate a department of Japanese history. In his answering memorial, Riess included information about the availability of Dutch sources preserved at The Hague and stressed the necessity of obtaining copies for the Bureau of Historical Compilation (former Shushikyoku 修史局), which had just been transferred from the Cabinet to the University's Faculty of Letters (Bunka Daigaku 文科大学). This advice was promptly accepted, and a diplomatic route was established to receive some handwritten copies of "General Missives sent from Batavia" at the University Library. Unfortunately almost all of them were destroyed in the great earthquake in 1923. 2.Riess himself made a personal search for documents when he visited Europe on leave in 1893. He visited The Hague, London, and Rome and sent back some excerpts of Dutch manuscripts, again via the diplomatic route. Although they were too destroyed in 1923, that was the beginning of the practice of visiting foreign archival institutions to locate originals and to collect handwritten copies. Naojiro Murakami 村上直次郎 (1868-1966) and many other students followed their teacher's way. 3.Riess published articles both in English and German in Tokyo and many were translated into Japanese by his students and printed for the use of the Japanese audience. As seen through the bibliographical information given in this present article, these represented the style of historical articles to be followed by Japanese scholars and also stimulated the evaluation of foreign sources for the study of Japanese history as well as international relations. Riess' efforts laid the corner stone for the prospective study and compilation of foreign documents at the University of Tokyo. Especially, the Historiographical Institute (Shiryo Hensan-jo 史料編纂所) has continuously been working by microfilming with international co-operation provided through the offices of the Japan Academy.