Nidaros is a diocese in the Lutheran Church of Norway. It covers Trøndelag county in Central Norway and its cathedral city is Trondheim, which houses the well-known Nidaros Cathedral. Since 10 September 2017, the Bishop of Nidaros is Herborg Finnset. The Bishop Preses, currently Olav Fykse Tveit is also based at the Nidaros Cathedral. The diocese is divided into nine deaneries (prosti). While the Bishop Preses holds episcopal responsibility within the Nidaros domprosti (deanery) in Trondheim, the Bishop of Nidaros holds episcopal authority of the other eight deaneries as well as the language based parish of the Southern Sámi.

The diocese of Nidaros was established in 1068. It originally covered the (modern) counties of Trøndelag, Nordland, Troms, and Finnmark, along with the regions of Nordmøre and Romsdal (in Møre og Romsdal county) and Härjedalen (in Sweden), and also the northern part of Østerdalen (Tynset, Tolga, and Os). The region of Sunnmøre (in Møre og Romsdal) was transferred from Diocese of Bjørgvin to the new Archdiocese of Nidaros some time after 1152 – to secure it more income.

The northern part of Østerdalen was transferred to the Diocese of Oslo some time after 1537. The province of Jämtland was transferred from Diocese of Uppsala to Nidaros in 1570. The region of Sunnmøre was transferred (back) from Nidaros to the Diocese of Bjørgvin in 1622. The provinces of Jämtland and Härjedalen were lost to Sweden in 1645. Northern Norway was established as a diocese of its own in 1804 (formally first in 1844). The parish of Innset was transferred from Diocese of Hamar to Nidaros in 1966. The regions of Nordmøre and Romsdal (together with Sunnmøre from Bjørgvin) were established as a diocese of its own (Diocese of Møre) in 1983.

The Diocese of Nidaros is divided into nine deaneries (Norwegian: Prosti). Each one corresponds to several municipalities in the diocese. Each municipality is further divided into one or more parishes which each contain one or more congregations. In addition, the Parish of the Southern Sámi language area fall under the Bishop of Nidaros authority, while the Trondheim parish of the Deaf is pastored by the Deanery of Church of the Deaf and the Bishop of Oslo.^[1]

The bishops of Nidaros since the Protestant Reformation when Norway switched from Catholicism to Lutheranism:

• List of Lutheran dioceses and archdioceses