Peter Cardy will step down as chief executive of Macmillan Cancer Support in December after five years at the helm.
Judy Beard, director of fundraising, marketing and communications at the charity, will act as interim chief executive from 1 January until a permanent appointment is made.
Cardy, who joined from the Multiple Sclerosis Society, said that he was looking for another job. "It would be nice to take a different direction, but I'm not ruling anything out," said Cardy.
"I'd like a break after Macmillan. When I decided to move I realised I haven't stopped in 40 years."