The Australian dollar has hit 100 Japanese yen for the first time since May 2013.

The Aussie dollar has been steadily climbing against the yen since October 31, when the Bank of Japan unexpectedly announced it would increase its massive bond-buying program in a bid to kickstart its sluggish economy.

The BoJ said it had ramped up its bond-buying program by as much as 20 trillion yen ($A196.92 billion) a year, to 80 trillion yen.

On Wednesday morning, the Australian dollar reached 100.48 yen – its highest level since May 22.

It’s one of the few times since the early 1990s that the local currency has passed the 100 yen milestone.