Harry Potter author's chair in auction

The chair JK Rowling sat on while writing the first two Harry Potter books is set to go under the hammer in New York.

The chair J.K. Rowling sat on while writing the first two Harry Potter books will go up for auction. (AAP)

The humble chair JK Rowling sat on while writing the first two books of the Harry Potter series will go up for auction in New York City on April 6.

But Muggles will have to dig deep, with the opening bid at the Heritage Auctions sale sitting at $US45,000 ($A60,741.04).

It's one of four old chairs given to the writer in 1995 for her flat in Edinburgh, Scotland, and was used while she penned Harry Potter and the Sorcerer's Stone and Harry Potter and the Chamber of Secrets.

It's embellished and signed by Rowling in gold and rose colours.

She also painted on the seat, "I wrote/Harry Potter/while sitting/on this chair."

Heritage says the seller is an English collector who wishes to remain anonymous.