According to People, Kutcher, who was married to Moore from 2005 to 2013, “pretty much ignores” the book.
“He is busy with a full life and has moved on,” one source close to Kutcher told the magazine.
In Inside Out, Moore alleges that Kutcher cheated on her with a 21-year-old woman whom she says he met during a family outing at a bowling alley.
She also alleges that Kutcher at one point “expressed his fantasy of bringing a third person into our bed”, resulting in threesomes.
In the memoir, Moore links that experience with Kutcher’s alleged infidelity, writing: "Because we had brought a third party into our relationship, Ashton said, that blurred the lines and, to some extent, justified what he’d done."
Kutcher is now married to his former That ‘70s Show co-star Mila Kunis, with whom he has two children.
People previously quoted a source as saying of Kutcher: "Ashton has never spoken about [Moore].
"He hasn’t talked about her since the divorce, and he never will. He respects that she’s a mother with a family."
The Independent has contacted Kutcher’s publicist for comment.