The article puts forward arguments that challenge the legitimacy of the ontological interpretation of music worked out by Roman Ingarden. This interpretation assumes that the existential, aesthetic, and axiological nature of music is determined by the ideal structure of a musical composition, independent of the real world and existing as an element of the transcendental consciousness that defines its timeless identity. According to the author, this argument does not have adequate justification either in the history of research on the nature, genesis, and functions of music, nor in considerations that make an attempt to explain its meaning. However, the category of the identity of a musical composition is not a completely unfounded idea. It is found in research referring to many supplementary methods in which it is treated as a rational postulate that makes it possible to determine what should actually be considered and taken into account in situations that demand examinations or modifications of statements concerning the identity of a musical work.