Jun-iti Nagata (長田 潤一, Nagata Jun'ichi, 1925 - 6 November 2007) was a Japanese mathematician specializing in topology.

Dr Jun-iti Nagata
長田潤一
Jun-iti Nagata in 1977
Born	1925 (1925)
Died	November 6, 2007(2007-11-06) (aged 81–82)
Nationality	Japanese
Occupation	Mathematician
Known for	Nagata–Smirnov metrization theorem
Title	Professor emeritus
Academic background
Education	PhD
Alma mater	Osaka University
Doctoral advisor	Kiiti Morita
Academic work
Discipline	Topology mathematics
Institutions	Osaka Kyoiku University, Osaka Electro-Communication University
Notable works	Modern Dimension Theory, Modern General Topology

In 1956, Jun-iti Nagata earned his PhD from Osaka University under the direction of Kiiti Morita. He was the author of two standard graduate texts in topology: Modern Dimension Theory^[1] and Modern General Topology.^[2] His name is attached to the Nagata–Smirnov metrization theorem, which was proved independently by Nagata in 1950 and by Smirnov in 1951, as well as the Assouad–Nagata dimension of a metric space, which he introduced in a 1958 article.^[3]

Nagata became a professor emeritus at both Osaka Kyoiku University, where he taught for 10 years, and Osaka Electro-Communication University, where he taught for 5 years.