Rowling's seven Potter books have sold more than 400 million copies.
Her most recent fantasy novel "Harry Potter and the Deathly Hollows" was widely believed to be the last in the series but Rowling hinted in an interview with U.S. television chat show host Oprah Winfrey that she might at some point continue the franchise, the Telegraph reported Friday.
Explaining how the characters from the books are "in my head still" and one day she "could definitely" write new books about them, she said: "I'm not going to say I won't. I love writing them.
"I have to write for my own mental health. I need to write. I love it. I need to do it," she said.
Finishing "Deathly Hollows" "was huge," she recalled.
"Even though I knew it was coming. Initially I was elated, but then I cried like I haven't cried since my mother died," the newspaper quoted the author as saying.