Welsh Rugby Union (WRU) operations director Julie Paterson will become the latest senior figure to leave.
Paterson has been confirmed as the new Six Nations director of rugby and will start in the summer of 2021.
In the last six months, chairman Gareth Davies, chief executive Martyn Phillips, performance director Ryan Jones and commercial director Craig Maxwell have left the WRU.
"It has been an honour to work in Welsh rugby," said Paterson.
Paterson will take up her new role after finishing her position with the WRU.
She chaired the Rugby Management Board in Wales and is a member of the Professional Rugby Board (PRB). She also sits on the Pro14 executive board and represented Wales on the World Rugby council.
"I am immensely proud of my time at the union but am hugely excited by the challenges and opportunity presented by this new role," said Paterson.
"The Six Nations is unique and I look forward to playing my part in ensuring as a collective we continue to move rugby forward and go from strength to strength."
The Six Nations say the director of rugby role will "oversee the collective strategy in regards to global rugby matters, in addition to the rugby strategic direction and rugby operational matters for the championships at all levels".
"Her knowledge of rugby is vast, and her expertise will be a fantastic asset for our organisation," said Six Nations Rugby chief executive Ben Morel.
"She will be a valued addition to our existing leadership team, and I am looking forward to working with her on the development of our sport."
WRU interim chief executive Steve Phillips added: "We wish Julie all the best in her new role with the Six Nations.
"Her 31-year stint at the WRU was impressive and accomplished.
"While we are sorry to see her leave, it is great she is staying in the rugby family.
"I have no doubt she will be as successful in this new position as she was at the WRU and has my full support and that of everyone at the union."