More than two out of three businesses polled said the UK economy would benefit from staying in the EU.
The survey of 553 organisations by Reed Personnel Services showed more support for leaving the EU in the South-west, while firms in the Midlands were most in favour of staying in. Larger firms were more likely to argue in favour of remaining in Europe.
Labour's trade and industry spokeswoman Margaret Beckett said: "This survey is overwhelming evidence that the business community recognises the need for Britain to play a constructive role in Europe and recognises also the danger to prosperity and jobs if we were to leave the EU. It thus shows the dangers to which Tory divisions on Europe expose Britain, risking 3.5 million jobs."
The survey also found that senior managers were keener on the staying in Europe than lower ranks, with only 17 per cent of them wanting the UK to leave the EU, compared to 24 per cent of middle managers and 25 per cent of support staff.
There were also differences between business sectors, with 76 per cent of manufacturing businesses thinking the UK should stay in and 19 per cent that it should leave, compared to 60 per cent of distribution and wholesale organisations believing the UK should stay and 31 per cent that it should get out. A quarter of service and retail business and 24 per cent of public sector organisations thought leaving the EU would be better for the UK, along with 17 per cent of charities.