The Music department of the Staatsbibliothek holds the largest music collection of Germany which is also one of the world's most important music collections. The collection does not only include autographs and manuscript copies of composers, among them J. S. Bach, G. Ph. Telemann, W. A. Mozart, J. Haydn and L. van Beethoven. The importance of the collection also lies in the large number of estates, deposits, and the collection of letters from composers, music scientists etc. Main activities of the music department also involve the collection of specialised literature and periodicals on music, modern and antiquarian sheet music, libretti, and sound carriers. In addition to that the music department is responsible for a specific period of time "Noten von 1801 bis 1945" (music scores from 1801 to 1945) of the national project "Sammlung Deutscher Drucke" (Collection of German Prints).

The Mendelssohn archive is affiliated to the department. Founded in 1964, the archive has been the central repository and documentation centre for the life and works of the Mendelssohn family.

Besides acquiring items for the collections, further tasks of the department are: recording and classification of the items in catalogues and databases - StaBiKat for books, journals and sheet music, Kalliope for manuscripts and RISM for music manuscripts. Staff members make items available in the music reading room, give information regarding the holdings, and make reproductions for an international audience of musicological readers.