Benhamou also enjoys a housing allowance and family benefits, Le Canard reported.
The balding 61-year-old president, long the target of gossip over his "unnaturally youthful" jet-black hair, and already the most unpopular French leader in modern times, has now become the butt of jokes that his barber charges extra for implants or "miracle extensions".
The President's office confirmed his barber's pay but refused to comment on dye or implants.
The government spokesman, Stéphane Le Foll, said: "He is always with the President."
A palace official justified Benhamou's pay by his long hours, explaining that he attended to the President's hair every morning "and as many times as necessary, for every public appearance".
The "coiffeur" is also sworn to secrecy about the nature of the work performed and any information he may glean in the course of his duties.
Required to travel with Hollande on trips lasting longer than one night, the hairdresser can take few holidays because he has no stand-in and is "at the President's disposal 24 hours a day", Benhamou's lawyer told the newspaper.
"He missed the birth of his children, their broken bones, their operations."
The lawyer, Sarah Levy, said Benhamou's exclusive contract had forced him to sell his hairdressing salon in the wealthy 17th arrondissement of Paris for a "knockdown" price.
Le Canard concluded that "looking after that rare treasure, the presidential hair, is no sinecure".
Hollande, whose portly figure and slicked-back hairstyle often prompt comments that he resembles a provincial bank manager, faces almost certain defeat if he manages to win a Socialist Party primary and run for re-election as president next year.
He was lampooned for wearing a crash helmet to be dropped off by scooter at assignations with his girlfriend, the actress Julie Gayet, and the latest palace scandal will further damage his reputation and prospects.
The far-right Front National, which has achieved unprecedented gains during Hollande's presidency, was quick to exploit the scandal, saying it revealed the "disconnect" between the government and the French people.
"We've reached the limits of indecency," said Nicolas Bay, the party's secretary-general.
On Twitter, critics were merciless, quickly dubbing the story #coiffeurgate - or hairdressergate.
Some posted mocked-up pictures of the president with a mullet or a perm.
One user joked that he was grateful Hollande had so little hair, otherwise he dreaded to think what the cost might be.
"We elected a president, not a king," another tweet said.
A picture was posted of Hollande running his fingers over his hair with the caption, "This isn't just a dye job. This is a work worth half a million euros".