The Museum Society was established in Škofja Loka in 1937 and immediately began collecting museum and archival material. The society opened its first museum collection in 1939 and within it archival items were also exhibited. After a pause during World War II, the Museum continued with its professional activities in 1948 and in 1950 a historian was employed to work as an archivist. In 1966 a law was enacted to entrust the preservation of the Municipality of Škofja Loka's archives to the Municipal Archives of Ljubljana (since 1973 known as the Historical Archives Ljubljana). Because of the importance of the archives in Škofja Loka, an independent archivist was employed there. In 1973 the Historical Archives Ljubljana organised a special unit in Škofja Loka. Two years later the archive was moved from the castle to new premises in the building of the former monastery.
In 2004 the archives again got new premises in the place of the former army barracks.
Today two archivists collect and preserve the archives of the region of Škofja Loka together with those of some new municipalities (Gorenja vas-Poljane, Škofja Loka, Železniki, and Žiri).
In addition to the old archives, which were taken over by the Museum Society before the second world war and by the museum after the war, the archival holdings are constantly complemented by records of counties, courts, schools, factories, institutions, societies, etc.
The unit has issued a number of publications on the local history of Škofja Loka and surrounding areas.
The unit holds 350 archival items, comprising some 570 linear metres of records and some older documents from the Munich archives on microfilm. A reference library, a microfilm laboratory, and copying machines are available for public use.
The unit keeps the most archives from before the war and post-war administration in Škofja Loka, land registries since 1780, notary documents from 1852 until the Second World War, and some family and personal documents (part of the archives of Ivan Tavčar) and a microfiche collection on the Freising domination. Among the oldest documents are guild documents from 1522.
There was a resounding exhibition in 2008 of Judita Šega Protestantism in Loka district: The 500th Anniversary of the Birth of Primož Trubar.