Bam Construct managing director Richard Bailey is leaving the company on 1 August after a 39-year career.
The company said Mr Bailey, 60, was leaving to pursue interests elsewhere.
He joined Bam in 1977, became western regional director of Bam Construct in 1995 and joined the board in 2007.
Mr Bailey was appointed managing director of Bam Construct in 2010.
Chief executive Graham Cash said: “Richard has been a tremendous supporter of people and he has been a pioneer of countless new ideas from developing sustainability to zero harm to lean [construction] to collaboration.
“Many people in the company regard Richard as a friend and mentor and he will be missed by all.”
Douglas Keillor will join the board in Mr Bailey’s place, serving alongside Mr Cash and the other executive director James Wimpenny, a spokeswoman said.
Mr Keillor joined the company in 1990 and became regional director of Bam Construct in Scotland in 2013.
A successor to his Scotland post will be named later in the year.