He said: 'That couldn't be further from the truth. We have made great changes in recent years. We have a younger membership, strong representation from the public sector and charities.
'Our members are at the heart of debate. The task now is to really push that image.
We are more sushi-bar than pin-striped suits,' he added.
The director of public affairs post is a newly created role and comes following the decision by IoD director of communications Steve Reardon to retire.
Cox said he also hopes to see more publicity gained from the IoD's research into government policy.
Two years ago, its research into the future of the NHS gained a great deal of exposure, Cox said: 'We are doing a lot of work on the policy side and expect to release a lot of information soon on issues such as health, transport, equal opportunities, employability and education.'
The director of public affairs role will continue overseeing Reardon's key areas of lobbying and image management.
Reardon will stay in post until mid-summer, by which time a new director of public affairs is expected to be in place.
Reardon heads a three-strong team and reports to Cox. The recruitment process is being handled by headhunting firm Electus.
Whoever fills the newly created role will work alongside Caroline Dyer, director of communications for the IoD's enterprise arm and Ruth Lee, the body's head of policy.