Introduction of reinforced concrete was a very important turning point in the history of elevated railway viaducts in Japan. Dr. Mikishi Abe (1883-1965) was one of the key persons to spread this technology. He entered Government Railways after graduating from the Department of Civil Engineering, Sapporo Agricultural College, in 1905, and went to lllinois University to study the newest technology about reinforced concrete. He returned to Government Railways from the U. S. in 1914, and designed the widest span arch bridge made by reinforced concrete in Japan. But his name was well known only in the architectural field before he became independent as an architect in 1920. Therefore, this report describes his achievement in the civil engineering field and his role as a civil engineer. From the results of this study, it is clear that he made an important contribution to the development of elevated railway viaducts.