Mr Saines has been in the role since March 2015 and has played a key role in the success of the funds management business, Challenger said in a statement to the ASX.
It said it has begun an internal and external search for his successor, with Mr Saines working closely with the appointee to ensure a smooth and seamless transition.
“Ian will retire from Challenger later this year confident in the knowledge that he has built a talented team with the depth, strength and capability to continue to grow the business and to capture the opportunities ahead,” said Challenger managing director and chief executive Richard Howes.