Béla Balázs, the librettist of Béla Bartók’s Bluebeard’s Castle and Wooden Prince, wrote many remarks about Bartók in his recollections throughout his life, and their manuscripts are preserved in Budapest, in the Library of the Hungarian Academy of Sciences and National Széchényi Library. Some parts of these texts, however, still remain unpublished. Even though his reminiscence tends to exaggerate their friendship, which in fact ended in their earliest period in Budapest, examination of the sources provides us with a new understanding of the relationship between the librettist and the composer. Therefore, this paper introduces the documents written by Balázs, gives a selective overview of their friendship, and examines how the image of Bartók changed in Balázs’s mind over time.