Mr. McCarthy, 76, has won a wagon-full of honors including a Pulitzer Prize, a National Book Award and the MacArthur Foundation’s so-called genius grant. Books like “Blood Meridian,” “All the Pretty Horses” and “The Crossing” have propelled him to the top ranks of American fiction writers.

Image Cormac McCarthy is finally giving up this particular typewriter. Credit... Christie's

Even nonreaders are familiar with his storytelling since his two most recently published novels, “No Country for Old Men” and the 2007 Pulitzer winner “The Road,” have been made into movies. (“No Country” won best picture and three other Oscars last year.)

Christie’s, which plans to auction the machine on Friday, estimated that it would fetch between $15,000 and $20,000. Mr. McCarthy wrote an authentication letter  typed on the Olivetti, of course  that states:

“It has never been serviced or cleaned other than blowing out the dust with a service station hose. ... I have typed on this typewriter every book I have written including three not published. Including all drafts and correspondence I would put this at about five million words over a period of 50 years.”

Speaking from his home in Santa Fe, Mr. McCarthy said he mistakenly thought that the typewriter was bought in 1958; it was actually a few years later. He had a Royal previously, but before he went off to Europe in the early 1960s, he said, “I tried to find the smallest, lightest typewriter I could find.”

Mr. McCarthy is known for being taciturn, particularly about his writing. He came to realize that not only his working method but even his tools are puzzling to a younger generation.