The Finnish linguist G.J.Ramstedt is well known for his pioneering role in establishing the field of Altaic comparative linguistics, as well as serving in a diplomatic capacity as the first charged'affaires at the Finnish legation in Japan from 1919 to 1929. It was during this ten-year stay in Japan that he concentrated his efforts on attempting to discover the origin of the Japanese language and published a treatise on his research in 1924. In writing this article, I surveyed a range of topics, not only those included in Ramstedt's research findings, but also those in the similar stream of studies by his predecessors, as well as observations and evaluations of his work made by other comparative linguists. Ramstedt's work was carried out through comparisons of the various aspects of the Altaic languages, and outlines a solid and potent methodology of establishing a possible genetic relation between Japanese and the Altaic languages. Ramstedt's work laid strong foundations and had a promising start. Although his work was never completed and so had potential for further development and expansion, no satisfactory progress had been made in comparative study of Japanese, as he himself pointed out in his letter addressed to the Japanese linguist Shichiro Murayama.