A knife-wielding woman broke into a Seoul theatre dressing room and injured prominent K-pop star Kyuhyun during a struggle.
She broke into the room at about 18:00 local time (09:00 GMT), local media reported.
Kyuhyun, a member of the boy band Super Junior, was visiting his fellow actors at the time and was cut on his finger while attempting to restrain her.
The woman, who is in her 30s, has been arrested.
The police are investigating where she got the weapon and whether she has a history of mental illness.
She reportedly has no connection to Kyuhyun or any of the other actors who were present, local media said.
"Kyuhyun suffered a small cut on his finger, which was treated right away on site," the 35-year-old's celebrity agency Antenna Music told South Korea's national newspaper JoongAng Daily.
Kyuhyun is currently starring as the lead actor in a Korean-language version of the Ben-Hur musical, which tells the story of a fictional Jewish hero who was falsely accused of an assassination attempt by the Romans.
The actor-singer joined Super Junior, one of the country's most popular boy bands, in 2006.
Since then, he has also established himself as a musical actor.
