About 15 men have been arrested in the attack, which occurred Friday evening in a remote forest area in Madhya Pradesh state, The Times of India reported.
A group of men set upon the couple as they set up camp for the night, police said. The tourists had bicycled from Orchha, a town known for its temples.
The husband said four men raped his wife while the others held them both down. He said he and his wife were beaten and robbed of a laptop computer and camera, cellphones, flashlights and their money.
The 39-year-old woman was examined at Gwalior district hospital, where the sexual assault was confirmed, police said.
The couple had been in India for about three months.
Exploding whale video goes viral on Internet
Gal Gadot cast as Wonder Woman for 'Batman vs. Superman'