Martin has been at the helm of the £150m turnover contractor for the last 10 years.
He is moving at the end of this year to become director general at the Institute of Directors.
John Clugston, chairman of The Clugston Group, said: “Stephen has been a most effective and loyal CEO and whilst we are sorry to see him leave The Group, we are delighted he will be taking up such a prestigious appointment.
“Once Stephen’s successor has been selected a further announcement will be made by The Group.”
Clugston has started the hunt for a successor and in the meantime Martin will continue to run the group.