The man was arrested in connection with an Aug. 8 attack on an 11-year-old girl as she slept in a tent, Radio France Internationale reported.
After his arrest, the man, who was not identified in reports, confessed to four other assaults of girls in an area popular with campers, police said.
In the latest attack, the girl was sleeping with her younger sister at Saint-Didier-sous-Aubenas in the central Ardeche region. They were in a tent next to a caravan occupied by their parents.
Three of the victims were French, one was Dutch and one German, police said.
DNA helped track the man to his home in the village of Brune, a prosecutor said.
Neighbors said they notified police 18 months ago that the suspect had been downloading images of child pornography.
A prosecutor told reporters just hours before the Friday arrest there was no evidence of a serial rapist operating in the area, the report said.