The woman, in her 30s, came forward when two amateur photographers discovered the chamber in the cellar of an abandoned farmhouse north of Halmstad in western Sweden, the Swedish news agency TT reported Monday.
Because of the nature of the case, the woman and her captor were not named, the report said.
The woman said she was kidnapped from a highway service station in 2005, with the man first taking her to a barn and then to the abandoned house. She said she was taken into the underground chamber, where she was handcuffed, chained, whipped and sexually abused repeatedly.
Investigators said the woman was kept in the cellar for several days. It was unclear why she didn't file a complaint sooner or how she escaped from her captor.
Prosecutors said the chamber was equipped with sex toys and a bed fitted with harnesses and ropes that could be used to hold people against their will.
The court Monday sentenced the 47-year-old man to five years in prison for aggravated rape and abduction and ordered him to pay more than $35,000 in damages to his victim.