The study deals with the typological polarization of music-museal institutions. In the background of past and present music-museal institutions, we recognize two ideal, fundamental types: the music museum and the music library. The differences between the two types are manifested at all levels of musealisation. Music museum is an institution that uses artefacts and secondary information to build a model of a certain combination of aspects of musical culture, thus enabling to learn about a given area of musical culture in a negative (aesthetic) way. Music library is an institution that builds a system of mentefacts and secondary information, enabling to learn about musical culture on the basis of an effective work with musical information (music as information and information about music).