Adrian Coles, director-general of the Building Societies Association, is stepping down after 20 years in the role.
Mr Coles is expected to leave later this year and a search has begun for his successor which the BSA expects will take all year.
He first joined the BSA as an economist in 1979 and has worked as director-general since 1993.
Mr Coles said: "I have enjoyed, and continue to enjoy, being the BSA's director-general, a position I hold with considerable pride. However, now is the right time for me to seek to develop my career in other ways. I have held this post for 20 years, and it is time for a change, both from my point of view and that of the Association.
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"A new regulatory regime will be in place shortly and it is right that a new leader takes the BSA into this new age. Also, the mutual sector is recovering strongly after a difficult period in the financial and mortgage markets, giving my successor a very strong base from which to work."
David Webster, chairman of the BSA, said: "Adrian has been an outstanding ambassador for the mutual sector since joining the BSA as an economist in 1979, and he has played a pivotal role in guiding our industry through good times and tough times.
"Adrian has shaped the BSA into a robust, professional and respected organisation. He will be a tough act to follow and we wish him every success in his future career."

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