0430 GMT December 12, 2019
The asking price for the handwritten score dating from 1772 has been set at 150,000-200,000 euros (USD 166,000-220,000), the auction house said.
It goes on sale on November 18, AFP wrote.
"It's the only version," said Simon Maguire, a specialist in musical manuscripts at Sotheby's in London.
The manuscript has never been published and the autograph score contains a few corrections and minor modifications, including one or two that might be in the hand of Mozart's father, Leopold.
The manuscript was kept in Salzburg by the composer's sister, Nannerl, and later found its way into the vast collection of Austrian writer Stefan Zweig, who was "a legendary collector of musical fragments, notably those by Mozart," Maguire said.
The score is being sold as part of the library of the eminent Swiss bibliophile, Jean-Francois Chaponniere.
Mozart, a child prodigy, began composing at a very early age under his father's guidance.
On November 27 and 28, a portrait of the 13-year-old Mozart is also going up for sale at rival auction house, Christie's, again in Paris.
It is one of the very rare contemporary portraits of the composer still in private hands and the bidding price has been set at 800,000 to 1.2 million euros.