The 1977 novel was adapted for the big screen three years later, directed by Stanley Kubrick and starring Jack Nicholson.
According to Contactmusic, King confirmed that he is writing the follow-up during an appearance in Toronto this week. The story will apparently be set 40 years later and focuses on the lead character Jack Torrance's son Danny.
The update is currently going under the working title of Doctor Sleep.
King also admitted that he is nervous about penning the sequel to one of his best known works, adding: "Maybe if I keep talking about it I won't have to write it."