Nihon University , abbreviated as Nichidai (日大), is a private research university in Japan. Its predecessor, Nihon Law School, was founded by Yamada Akiyoshi, the Minister of Justice, in 1889. It is one of Japan's leading private universities. The university's name is derived from the Japanese word "Nihon" meaning Japan. Nihon University now has "16 colleges and 87 departments, 20 postgraduate schools, 1 junior college which is composed of 5 departments, 1 correspondence division, 32 research institutes and 3 hospitals." The number of students exceeds 70,000 and is the largest in Japan.

Count Yamada Akiyoshi was a Japanese politician, samurai, and one of the early leaders of the Meiji Restoration. He served as Minister of Justice from 1885 to 1891. In his youth he was commonly known as Yamada Ichinojō; however, he changed his name frequently during the Bakumatsu period.