The 62-year-old star thinks it is a mistake that four US states have chosen to decriminalise the drug and hopes that Britain does not choose to follow suit, reported Female First.
"Anything that alters your mental state I don't think should be allowed," she said.
The TV personality - whose husband Ozzy Osbourne has struggled with drug and alcohol abuse in the past - claimed making cannabis legal will result in more accidents.
"The next thing I am waiting for is when someone is working heavy machinery, when they are driving a car. It is all going to end in tears," Sharon said.
"In years to come there will be new laws for those who are smoking and using marijuana. This will end not the way everybody thinks it will."
The former "X Factor" judge's comments come after a number of celebrities including Susan Saradon and Amanda Seyfried called for the drug to be legalised across the United States.