Bruno Dey was handed a two-year suspended prison sentence by a court in the German city of Hamburg.
Dey had manned a tower at the Stutthof Camp in what was then occupied Poland.
Denying the charges, Dey had told the court: "I didn't contribute anything to it, other than standing guard. But I was forced to do it, it was an order".
He was being tried in a juvenile court because he was 17 at the time the atrocities were carried out, between August 1944 and April 1945, according to the indictment.