Frantz began playing piano at the age of ten and later studied with Eliza Hansen and Wilhelm Kempff at the Hochschule für Musik und Theater Hamburg under a scholarship from the Studienstiftung des deutschen Volkes, or German National Scholarship Foundation. In 1967, Frantz and Claus Kanngießer won the second prize at the international music competition of the ARD playing as a cello and piano duo, marking the beginning of his international career. He first played with the Berlin Philharmonic Orchestra, conducted by Herbert von Karajan in 1970. In 1975, he played in his United States debut concert with the New York Philharmonic Orchestra conducted by Leonard Bernstein, who became his lifelong friend. Other conductors with whom he has played include Carlo Maria Giulini and Rudolf Kempe. He founded the Schleswig-Holstein Musik Festival in 1986 and became a UNHCR Goodwill Ambassador in 1989, a post from which he has since retired. He also founded the Philharmonia of the Nations in 1995. From September 2013 Maestro Frantz serves as musical director of Israel Sinfonietta Beer Sheva.
He has two sons, Christopher Tainton, whom he had with pianist Carol Tainton, and Justus Konstantin Frantz, whom he had with Xenia Dubrowskaja.
- Festspiele Balver Höhle (1994 - 2007)
|Wikimedia Commons has media related to Justus Frantz.|
- Official website (Under construction) (in German)
- https://web.archive.org/web/20110719034821/http://archiv.handwerk-special.de/archiv/hw_spec/57_20.htm (in German)
- Interview with Justus Frantz, February 20, 1991
- Justus Frantz auf Mallorca: ´Ein Tag allein am Klavier - das ist Glück´ in: Mallorca Zeitung vom 22. Juli 2010