Film critic Mark Adams, who was in charge of the event for its 70th anniversary, is to leave the job with immediate effect.
His departure will leave the event - which was controversially moved out of its August slot in the calendar before Adams was appointed - looking for a new figurehead for the fourth time in 15 years.
However the hiring a new artistic director is to be delayed until next year under a shake-up which will see Rod White, head of programming at the Filmhouse cinema, which is jointly run with the EIFF, "oversee" next year's programme.
Recruitment of a new artistic director to take charge of the 75th festival in 2021, is expected to begin next year at some point.
Mr Adams' tenure has seen the festival's audience grow from around 46,000 in 2014, the year before he took charge, to more than 70,000 this summer.
He said today: "“It’s been a real pleasure to work with the team in Edinburgh and help deliver the growth and development of the festival over the last five festivals and to be instrumental in re-establishing its international profile. I've decided it's time to move on and look to new and exciting opportunities.”
Ken Hay, chief executive of the film festival, who was appointed eight years ago, said today: "Mark has played an important role in developing the festival over the last 5 years, introducing innovative programming and reaching new audiences.
"We're sorry to see him go, but are excited and ambitious for the future of EIFF.
"”I’m delighted that Rod has agreed to oversee the curation of the screenings programme of the 2020 festival. He has led the programming team at Filmhouse for the past 20 years, delivering a hugely rich and diverse programme for an increasingly broad audience. We can’t wait to see what he has in store for our 74th edition.”