The Chair of An Bord Pleanála, David Walsh, is retiring early on personal and family grounds.
Minister for Housing Darragh O'Brien has noted the decision and thanked him for his service, which spanned some 27 years between the board and the civil service.
The Minister said he will now move swiftly to initiate the process of appointing a new chair and deputy chair.
In a statement, Mr O'Brien said critical reforms are required to strengthen the board's systems and processes, and restore public confidence.
Sinn Féin spokesperson on Housing Eoin Ó Broin TD said Mr Walsh's resignation provides the Minister for Housing with an opportunity to wipe the slate clean at the crisis-ridden organisation.
"For months, An Bord Pleanála has been in crisis," Mr Ó Broin said.
"It has been clear for some time that the problems extended well beyond the behaviour of individual ABP members. There was, and continues to be, significant questions over the management, governance and culture operating within the organisation."
The news follows months of media and political pressure over revelations of malpractice and misgovernance in An Bord Pleanála.
The board has been beset by a litany of problems around conflicts of interests, interference in inspectors' reports and highly unorthodox composition of decision-making bodies.
In July, Paul Hyde, who was at the centre of a number of these allegations, resigned as deputy chair.
On Thursday, the Irish Examiner reported the Fórsa union representing inspectors at An Bord Pleanála has demanded publication of a recent internal report highlighting the malpractice.
Fórsa assistant secretary general Ian McDonald wrote to Mr Walsh to say working conditions have become “intolerable” for their members as a result of the ongoing controversy around alleged conflicts of interest at the board.
Fórsa, he said, would not accept “any attempts to whitewash any wrongdoing”, and that a number of its members “no longer had confidence” in some of the people in management positions.
