The former pro wrestler blamed a budget dispute for the move, saying state lawmakers left him no choice but to close the 20-room English Tudor residence when they cut his spending and reduced his security budget.
"I don't know how they can possibly force me to keep it open without the funding," Ventura said.
Lawmakers said they may seek an injunction to force the mansion to reopen.
"Hopefully, the governor will realize that the mansion is the people's house and he shouldn't just close it because he's mad at some legislators," said Rep. Matt Entenza.
Earlier Attorney General Mike Hatch issued an opinion that says state law requires Ventura to keep the 92-year-old mansion open and available for ceremonial purposes. But Ventura called that just an opinion and said he would go ahead with the closing.
Ventura and his wife, Terry, once used the mansion frequently, but now spend most nights at their horse ranch in Maple Grove.
Trying to close a deficit estimated at more than $2 billion, lawmakers recently enacted a budget over Ventura's veto that cuts $1.3 million from his $9.3 million office and security budgets. Ventura's aides said it would take $375,000 to run the mansion through the end of June 2003.
Ventura, a political independent, said the mansion would be maintained as required by law, but Entenza took issue with the governor's definition.
"When you fire the staff and haul out the furniture, you're not maintaining it as the law requires," the Democrat said.