Ringsaker is a municipality in Innlandet county, Norway. It is part of the traditional region of Hedmarken. The administrative centre of the municipality is the city of Brumunddal.

The municipality of Ringsaker was established on 1 January 1838 (see formannskapsdistrikt). The municipalities of Furnes and Nes were merged with Ringsaker on 1 January 1964.

The municipality (originally the parish) is named after the old Ringsaker farm (Old Norse: Ringisakr), since the first church was built there. The first element is the genitive case of ringir or ringi, of unknown meaning. One proposal is that Ringir or Hringir ("Lord of the Ring") may have been an epithet or alias for the Norse god Ullr, based on a ceremony mentioned in the poem Atlakviða where an oath is sworn by hringi Ullar ("the ring of Ullr").

The last element is akr, meaning "acre" or any "field" generally.