Iwanuma (岩沼市 Iwanuma-shi) is a city located in Miyagi Prefecture, Japan.
As of July 1, 2010, the city has an estimated population of 44,379 and a population density of 731 persons per km². The total area is 60.71 km².
The city was founded on November 1, 1971, and maintains a sister city relationship with Napa, California in the USA.
Iwanuma is home to the Takekoma Inari Shrine, the second-oldest shrine dedicated to the kami Inari.
It was seriously affected by the tsunami associated with the 2011 Tōhoku earthquake.
Iwanuma is located at the northern end of the Abukuma River.
Iwanuma is at the convergence of two ancient roads, the Tōkaidō (via the Pacific coast) and the Tōsandō (inland route), both originating in the Kansai region.