Taking ‘Being and music’(Sein und Musik) as the main talking point, this paper aims to examine Schopenhauer’s doctrine of music in the horizon of his life-philosophy, excavating the intimate relation between music and human-Dasein. A new understanding presented in this treatise is that Being reveals itself as music in the form time, so that humans as Homo musikus are ‘musical Da-sein’(musikalisches Da-sein) performing the understanding of Being(Seinsverständnis) through music.—music is a ‘supreme’ mode of existence in which human-Dasein performs it. To sum up, music is not a mere sensual amusement or contemplative art, but ‘ontological truth’ itself wherein the revealing and understanding of Being takes place. From this new perspective, I will investigate the preceding arguments critically. There have been some debates on Schopenhauer’s metaphysic of music—in terms of Romanticism, the aesthetics of feeling, or Hanslick’s idea of absolute music, in which process main controversial points were exposed. In those preceding debates we can often see Schopenhauer described as a theorist of absolute music, but this is not a very proper determination. Meanwhile, it was asserted by Dahlhaus that Schopenhauer took music as the “organ of philosophy”. This is directly related to the autonomy of music, which I will debate, focusing my criticism on Hanslick’s idea of absolute music. By penetrating into the depth of Schopenhauer’s philosophy, this research will reconsider the precedent assertions critically, and bring to light the existential significance of music for human-Dasein which is implied in his metaphysic of music.