The man is accused of renting out 35 rooms in the imposing Chateau La Tour near the pretty village of Saint-Pierreville in the southern Ardeche region on France's most popular Internet classified ads site, without the necessary permits or safety checks.
Around 100 tourists were staying at the chateau and its 13-place campsite when police raided and closed the hotel last week.
The hotel's owner, who was not named, had hired around a dozen staff, apparently off-the-books, police said.