The beginnings of records forming go back to 1935, when Museum society started collecting museum and archival material for a future museum of Novo mesto or Dolenjska. After WWII county records were founded. Since 1952 museum director also performs the duties of the records manager.

After passing The Archival material and records law in 1966 gradually all municipalities of Dolenjska and Bela krajina region entrusted Ljubljana historic records to keep their archive material. For Dolenjska and Bela krajina regions the Novo mesto unit was founded in 1973. Today, it comprises of four administrative units (Črnomelj, Metlika, Novo mesto and Trebnje).

There is very little preserved older materials. There is some more of it from the early 19th century on, mostly material of administration (district offices, county head offices, municipalities), courts of law, land registers, savings and loans, societies, schools and official documents. Between wars and WWII material is almost non existent. Materials from first post war years are reasonably well preserved, with exception of economic organizations files. The unit keeps offer 400 funds or around 1000 running metres of archival materials from the year 1621 onward. Viewers of historic records can also use a reference library, copying machine and the microfilm laboratory.