Richard Millet, who says he has read all 1,500 pages of Breivik's online manifesto in which the Norwegian lays out his world view, insists that he does not approve of the gunman's crimes.
However, Millet praised Breivik's writing and cry of hatred for social democracy, immigration and multi-culturalism.
"Breivik is without doubt what Norway deserves," wrote Millet in an 18-page pamphlet.
He is "as much a child of a broken family as of an ideological and racial fracture caused by immigration from outside Europe over the last 20 years," added Millet, who has edited several award-winning books in France.
His writing about Breivik has sparked consternation in the literary circles, with one author Annie Ernaux calling the text "a politically dangerous act".
Another author Tahar Ben Jelloun said: "He has lost his head."
Others were less critical.
"He is still my editor," said Alexis Jenni. "I don't want to take any public position on the subject. Millet believes only in literature.
"He is someone who writes marvellously well. His questionable ideas do not reduce his literary qualities," he argued.
Breivik was last week sentenced to 21 years in prison for killing 77 people in a bomb attack and deadly shooting rampage that shook Norway.