Arquivo Eclesiástico da Arquidiocese de Mariana, Episcopal archive in Mariana, Minas Gerais, Brazil

The Arquivo Eclesiástico da Arquidiocese de Mariana is an archive holding church records, administrative papers, and sacramental registers from the Archdiocese of Mariana. The collection documents roughly four centuries of religious and social history in the region.

The archive's holdings began in Mariana's parish church, later the cathedral, and moved through several buildings, including the first episcopal residence and the Casa Capitular. Archbishop Dom Oscar de Oliveira founded the Ecclesiastical Archive on 30 May 1965 at the Church of São Pedro dos Clérigos, separating permanent historical documents from current curial papers; its statutes were approved on 8 September 1965. In 1972 it moved to the new Curia building at Rua Direita and Rua Dom Silvério, and in late 2017 to the Palácio Getsêmani, reopening in 2018 as the Arquivo Eclesiástico Dom Oscar de Oliveira.

The archive holds parish registers of baptisms, marriages and deaths, plus marriage-dispensation and "de genere et moribus" inquiry files, brotherhood account books and entry lists. Through these, the daily life of Mariana, Ouro Preto and other Minas towns from the 18th to the early 20th century can be traced. Monsenhor Raimundo Otávio da Trindade, director from 1923 to 1944, was the first to treat the holdings as universal history.

Visitors should arrange an appointment in advance and bring personal identification including their CPF number. The collection is accessed on request for specific documents or topics rather than as open browsing.

Monsignor José de Souza Telles Guimarães (1840–1903) is credited with saving the archive's documents from a fire; the building itself is not recorded as having survived one. The archive also housed the Museum of Music from 1973 until 1988, when that collection moved to the Archiepiscopal Residence.