John O'Neill has quit his role as a director of the Rugby World Cup citing personal reasons.
The International Rugby Board (IRB) confirmed his resignation on Tuesday, effective immediately.
The former Australian Rugby Union boss and IRB council member has held the role since March 2012.
"It is with great sadness that the Rugby World Cup Limited Board has received and reluctantly accepted John's resignation," chairman Bernard Lapasset said in a statement.
"The Board would like to thank John for his exceptional contribution and his tireless dedication to strengthening the Rugby World Cup brand, profile and profitability for the benefit of the global game.
"There is no doubt that his vision, energy, expertise and leadership has been instrumental in delivering the strong foundations for what promises to be hugely successful Rugby World Cups in England and Japan, while driving forward a review of future delivery of our flagship event."
O'Neill wished the organisation every success for both next year's showpiece in England and the 2019 World Cup in Japan.
The appointment of a new director will be discussed at the IRB executive committee's next meeting in March.