**Michael Ira Rosen** (born 7 March 1938 in Brooklyn) is an American mathematician who works on algebraic number theory, arithmetic theory of function fields, and arithmetic algebraic geometry.

Rosen earned a bachelor's degree from Brandeis University in 1959 and a PhD from Princeton University in 1963 under John Coleman Moore with thesis *Representations of twisted group rings*. He is a mathematics professor at Brown University.

Rosen is known for his textbooks, especially for the book with co-author Kenneth Ireland on number theory, which was inspired by ideas of Andre Weil; this book *A Classical Introduction to Modern Number Theory* gives an introduction to zeta functions of algebraic curves, the Weil conjectures, and the arithmetic of elliptic curves.

For his essay *Niels Hendrik Abel and equations of the fifth degree* Rosen received the Chauvenet Prize.