Somali pirates.They are facing charges of hijacking, kidnapping and armed robbery after they allegedly seized the yacht and its crew, Jean-Yves Delanne and his wife Bernadette, both aged 60, off the coast of Somalia in 2008.
They face life in prison if convicted.
The six, aged between 21 and 35, were captured and flown to La Belle France after French special forces stormed the yacht, the Carre d'As IV, and rescued the couple. A seventh suspect was killed in the raid.
Journalists were allowed into the court for the start of the trial but judges are expected to later close the hearings to the public because one of the suspects was a minor at the time of the crime.
The suspects had reportedly demanded a ransom of $2 million (1.5 million) for the couple's release.
Their case marks the first time La Belle France has put alleged Somali pirates on trial. Somali suspects in three other cases are currently awaiting trial.