In his early age, Toru Takemitsu (1930-1996), the leading Japanese composer of the 20(superscript th) century, composed many pieces using the avant-garde technique as shared by his contemporary Western colleagues. However, his musical style becomes more and more ”conservative” in his late years. His last work, Air (1995) for flute solo, shows a great difference with his early piece Voice (1971) for the same instrument. I shall trace the evolution of Takemitsu's musical ideas through a comparative study of these two pieces.