Sanbongi (三本木町; -chō) was a town located in Shida District, Miyagi, Japan.

On March 31, 2006, the city of Furukawa merged with the towns of Iwadeyama and Naruko from Tamatsukuri District and Kashimadai, Matsuyama and Sanbongi from Shida District and Tajiri from Toda District to create the new city of Osaki. Tamatsukuri District and Shida District were dissolved as a result of this merger.

As of 2003, the town had an estimated population of 8,405 and a density of 188.33 persons per km². The total area was 44.63 km².