Chairman of JCB Lord Bamford has written to his company's 6,500 UK employees to explain why he favours a Brexit scenario.
In the letter he said he was "very confident that we can stand on our own two feet".
He also said that more than 53% of all UK exports go to non-EU nations, warning that the EU has a shrinking share of world trade.
The businessman says he supported joining the Common Market but did not back it turning into a political union.
Lord Bamford told his employees that the referendum's outcome "will determine the future of our country" with a "lasting impact on the lives of our children and grandchildren".
His letter states: "I voted to stay in the Common Market in 1975. I did not vote for a political union, I did not expect us to hand over sovereignty to the EU.
"I certainly did not expect unaccountable leaders in Brussels to govern over us.
"So do I wish to remain in an EU of diminishing economic importance as it moves towards ever closer union? Or do I want us to pull out of the EU, reclaim our sovereignty and regain control of how we trade with Europe and the world?"
The JCB chairman told workers it was up to them to make a choice, but urged them to vote in the referendum.
Trade has been a key issue during the debate on continuing EU membership.
On Tuesday, Roberto Azevêdo, director-general of the World Trade Organisation, warned Britain's trade agreements might have to 'start from scratch' in the event of a leave vote.
He added new trade agreements for a post-EU Britain could take time as all Britain's trade commitments had been negotiated by the EU and would cease to apply in the event of the country voting to leave.
