Tomio Kubota (久保田 富雄 Kubota Tomio?, born 1930) is a Japanese mathematician, who studies number theory. His contributions include works on p-adic L functions and real-analytic automorphic forms.
His work on p-adic L-functions, later recognised as an aspect of Iwasawa theory, was done jointly with Leopoldt.
He extended the concept of metaplectic group, in a way significant for arithmetic applications. This opened a field for later research on associated Dirichlet series and automorphic forms, and was a major step in the solution of Kummer's conjecture.