The Seigneur of Sark will not sell the island under any circumstances, he has said in a statement.
It follows recent media reports suggesting Michael Beaumont might be open to the sale of the Fief of Sark in the future.
He said: "I will not sell the fief under any circumstances for any sum, however high.
"I have no intention of reneging on my obligations accepted on my becoming seigneur."
Mr Beaumont said: "If Chief Pleas becomes unable to operate as a free democratic assembly due to external intimidation then I would give serious consideration to surrendering my lease to the Crown."
The island's government underwent significant reform in 2008, following a referendum after calls for change were made under the European Convention of Human Rights.
Those changes did not include the abolition of the feudal roles of Seigneur and Seneschal.
The billionaire brothers Sir David and Sir Frederick Barclay, who own the neighbouring island of Brecqhou, have been among those calling for more radical reform, including an end the feudal roles.
In 2010 the Seneschal stood down from his role as president of Chief Pleas as he was seen to have an "unfair" dual role because he is also the island's senior judge.
The role of Seigneur, or Lord, of Sark is a hereditary title. Mr Beaumont became the 22nd person to take up the position in 1974.
It dates back to 1565 when Queen Elizabeth I granted a fief for the island, on condition that it was kept free of pirates and occupied by at least 40 men who could carry arms.