NAMA has said that John Mulcahy, the head of Asset Management at the agency, is to retire from the end of next February.
Mr Mulcahy joined the National Asset Management Agency when it was set up in December 2009 as head of portfolio management.
He was appointed to the board of NAMA by the Minister for Finance in March 2012 and was appointed NAMA's head of Asset Management in April 2012.
A chartered surveyor, Mr Mulcahy has worked in all aspects of the property industry for over 40 years, most recently concentrating on property investment and asset management.
NAMA said that Mr Mulcahy will be succeeded by Mary Birmingham who is currently a senior asset manager in the agency and who has extensive experience of the property industry.
Frank Daly, NAMA chairman, said the agency will miss Mr Mulcahy "both personally and professionally".
NAMA chief executive Brendan McDonagh said it would have been very much more difficult to deal with the scale of the challenge the agency faced four years ago without the "undoubted expertise" of Mr Mulcahy.
"His deep understanding of the property markets, domestically and internationally, coupled with his innate calmness, wit, wisdom and guidance were immense assets to NAMA and to me personally," Mr McDonagh added.