The Constitutional Court has ruled the law criminalizing adultery is constitutional.
Only one of nine judges sitting on the court ruled in favor of abolishing the law Thursday.
The court said the law is necessary to preserve morals and the monogamous system, and to protect society from family problems and other ills that may arise from adultery.
But the court also said the law MIGHT be abolished in the future "in view of the legal codes in other countries and changes in Koreans' attitudes toward sex."
Opponents say punishment for adultery is unconstitutional and that it infringes upon a person's private life. Those who advocate maintaining the law, including some feminists, argue that it protects women and the family.
Most adultery cases are dismissed in the process of investigation or trial.
In Korea, adultery was made a punishable crime in 19-53.