A statement from his Paris press office says Hallyday, an entertainment icon for decades, is "under observation" for the infection linked to Nov. 26 surgery on a herniated disc.
The statement late Tuesday says he should be out in a few days but gives no other details.
Hallyday is on a multi-country tour called "Route 66," a reference to his age and homage to the American rock that has inspired his music.
Producer Jean-Claude Camus said on French radio that Hallyday's hospitalization could thwart his plans to spend the holidays at his chalet in Gstaad, Switzerland, where filmmaker Roman Polanski is under house arrest.
