Stagecoach North East MD Phil Medlicott, 53, has resigned after 16 years with the group, for a new, as yet undisclosed job.
Recruitment for a replacement has started. In the interim, Stagecoach UK Bus Strategy Director Clare Kavanagh will manage the firm.
Having begun his industry career in 1983, as a driver and then through a series of management posts in Birkenhead, Runcorn and London, he became Stagecoach Warwickshire MD, then Stagecoach South MD.
Mr Medlicott took over in the north east in June 2012, after John Conroy retired.
Says Stagecoach UK Bus MD Robert Montgomery: “Phil has made a significant contribution to the development of a number of our regional bus services across England.
“He has made a particularly strong impact in the North East where our package of low fares, good customer service and significant investment in new buses and new smart ticketing technology has helped deliver one of the highest levels of bus use in Britain. I would like to wish Phil well in the next stage of his career.”
Stagecoach North East operates local bus services in Newcastle, South Shields, Sunderland, Hartlepool and Teesside. The company, which has more than 1,400 employees, runs around 470 buses and carries 63 million passengers a year.