The 68-year-old chairman of Hyundai, Chung Mong-Ku, has been sentenced to three years in jail, having been found guilty of embezzling £56m.
Mong-Ku, who is boss of both Hyundai and Kia, was accused of having a slush fund for paying lobbyists, bribing politicians and also for his own use.
The trial has been seen as a symbol of South Korea's desire to fight corporate corruption. Hyundai Motor Company is crucial to the country's economy, and is responsible for around 70 per cent of its motor vehicle exports. The firm's shares dropped on news of the court's ruling. Mong-Ku is on bail, pending an appeal.