Mittenaar (German pronunciation: [ˈmɪtn̩ˌʔaːɐ̯]) is a municipality in the Lahn-Dill-Kreis in Hesse, Germany.

Mittenaar lies in the Lahn-Dill Highland. On Mittenaar's 3,518 ha (8,690 acres) live more than 5,000 people. About 45 km of roads connect the various centres. More than half the municipal area is wooded.

Mittenaar borders in the north on the community of Siegbach, in the northeast on the community of Bischoffen, in the east on the community of Hohenahr, in the southeast on the town of Aßlar, in the south on the community of Ehringshausen, in the southwest on the community of Sinn, and in the west on the town of Herborn (all in the Lahn-Dill-Kreis).

The community consists of the centres of Ballersbach, Bellersdorf, Bicken (administrative seat) and Offenbach.

The community of Mittenaar came into being on 1 January 1972 with the merger of the formerly independent municipalities of Ballersbach, Bicken and Offenbach. Bellersdorf was amalgamated on 1 April 1972.

Ballersbach had its first documentary mention in 1270. The Ballersbach Church (Capelle zu Ballersbach) was also most likely built in this time. That the chapel had some special importance can clearly be seen in the much bigger village of Seelbach being placed under it.

Ballersbach grew together over time from two centres, one around the Baalerstaa (Balder- or Baldurstein; "Baldur Stone") and the other to the south.

About 1500, the church was painted with wonderful frescoes that eventually disappeared over time.