Kevin Fewster is quitting as director of Royal Museums Greenwich (RMG), home of the country's renowned maritime museum.
He will leave in the middle of 2019, he said.
"Our highly successful 2014-18 corporate plan has just been completed and this offers an ideal moment for fresh thinking to inform the way forward," he added.
"It has been a privilege to lead this great museum over the past twelve years and to work with such talented and dedicated staff, volunteers and trustees.
