A 19th-century marriage document with signatures of French rulers Napoleon and Josephine Bonaparte will hit the market next month for the très grande price of $20,000, a New York collector said Tuesday.

Napoleon and his wife were witnesses to the marriage of Gen. August Hulin and Marie Jeanne-Louise Tiersonnier on May 30, 1804, in Paris.

The contract signed by Hulin and his wife amounted to a “19th-century version of a prenuptial agreement,” according to David Lowenherz, president of Lion Heart Autographs.

“It’s a contract, people (getting married) would literally make contracts like this — ‘This property is mine, this property is yours,’ ” Lowenherz said.

Lowenherz will show off his rare documents during a show at the Palm Beach County Convention Center, from Feb. 10 to 16.

He said he’s sticking to his $20,000 asking price — even if demand comes up a little short.