Günther Anders' philosophy of music, which is nearly forgotten, is presented and discussed here for the first time in a comprehensive manner. It proves to be highly original: starting from the musical situation in which the listener or musician finds themselves, Anders provides a phenomenology or existential ontology of music that is heavily influenced by Heidegger's analysis of existence in Being and Time, as well as Hegel. He describes musical existence as a specific form of non-being-in-the-world and develops a genuine music anthropology. His later philosophy of discrepancy, which includes critiques of technology and media, is significantly derived from this philosophical approach to music. Furthermore, Anders has made important contributions to the topics of music (or art) after Auschwitz and Hiroshima, as well as music and technical reproducibility.