The decision comes after another court ruled last month that Kasyanov's acquisition of the dacha was illegal.
Critics allege Kasyanov bought the dacha at a fraction of its market value shortly before he left office in 2004.
Kasyanov said the ruling was "totally unfounded" and the result of political pressure. He said he would appeal the decision but did not expect a favorable verdict.
Kasyanov served as prime minister during President Vladimir Putin's first term before he was replaced in 2004. He has since become a vocal critic of the Kremlin and has declared he will run for president next year.
(Interfax, AP, AFP)