Hansen's father Des had been ill for some time and the coach had not been part of the team's preparations this week for the Test at Lang Park in Brisbane on Saturday, which is a dead rubber after the All Blacks retained the trophy in August.
"The All Blacks family extend our deepest sympathies to Steve and his family at this very difficult time," All Blacks manager Darren Shand said in Christchurch on Tuesday.
"Steve and the family thank everyone for their messages and support and ask for privacy at this very challenging time."
All Blacks players and management have already said this week that Hansen's absence from the team had not affected their build-up, something Shand reiterated on Tuesday.
"We have been dealing with this on a day-by-day basis ... and the All Blacks have continued their preparations for the Test match against Australia as Des Hansen would want them to do," Shand added.
The All Blacks team will be named on Thursday with the squad leaving for Australia later that day.
The world champions, who have held the Bledisloe Cup since 2003, will be seeking their 17th successive victory, which will tie the record for the most wins by a top tier rugby nation.
The overall world record of 18 successive wins is held by Lithuania.
Hooker Keven Mealamu is expected to earn his 100th Test cap in the match, the third New Zealand player to do so after Mils Muliaina and captain Richie McCaw achieved the mark at last year's World Cup.