Naojiro Sugiyama graduated from French Law Course, Tokyo University (1903). Went to Europe (1905) and studied civil law and commercial law in France, Switzerland and Germany.
Sugiyama Naojiro was director of the Japan Comparative Law Research Institute. Appointed lecturer at the Peers' School, Hosei, Nihon, Waseda and Meiji universities.
In 1908 he was appointed assistant professor and then professor at Tokyo University. Took his doctorate (1918) and received honorary doctorates from universities in Paris, Lyons and Bordeaux.
Retired (1938) and became a director of the Franco-Japanese Society and the Maison Franco-Japonais. Made lecture tours in Europe (1926, 1933 and 1937) and attended an international law conference there.