Ok So-ri, who was handed a suspended jail term, had lost a battle in October to have the ban declared unconstitutional.

"I would like to say I'm sorry for causing so much trouble to society," a somber Ok told reporters after the verdict.

A district court in Goyang, near Seoul, handed Ok a suspended eight-month jail sentence, South Korean media reported, meaning she will not have to serve time. Ok's lover received a six-month suspended term.

There was no immediate word on any plans for appeal.

The sensational sex-and-celebrities case has been tabloid fodder for months, with Ok's challenge to the adultery law adding extra spice.

Last year, Ok acknowledged during a news conference that she had had an affair with an opera singer who was a friend of her husband for a few months in 2006. She stressed the affair was a result of her loveless marriage to actor Park Chul.