The maths teacher and the 14-year-old student, who was in his class last year, began chatting on Instagram on February before beginning a relationship in June.
For her parents, the teacher is a sexual predator, despite their daughter's claim that the pair are in love.
"She's a child who believes in love with a capital L. As a teacher he knew that and used it to seduce my daughter," her mother told AFP.
There is no minimum age of consent in France, which does not treat sex between an adult and a minor as rape unless there is proof of force.
Currently, sex with a minor aged under 15 is classified as sexual assault, punishable by up to five years in prison.
Adults wielding some form of authority over the child face stiffer sentences.
In a speech on sexism to mark the UN's International Day for the Elimination of Violence Against Women on Saturday President Emmanuel Macron said he wanted a minimum age of consent of 15.
First lady Brigitte Macron, who was once the president's drama teacher, has also vowed to play a part in combatting sexual crimes and sexism.
In recent years there have been several trials in Western countries involving teachers who slept with students, the most famous being that of American woman Mary Kay Letourneau.
Letourneau was a 34-year-old married mother of four when she began a relationship with a 12-year-old student whom she later wed.
She served seven years in jail for unlawful sex with a minor.