Official figures show an average of 700 attempted attacks a month in 2010, up from 200 a month in 2009, according to Australian reports.
More than 5500 attacks were recorded in the first eight months of 2010 compared with 2400 for the whole of 2009, an increase of at least 230%.
The Australian military has not released any details of who is behind the attacks, but said there is evidence that dozens of countries are involved.
Officials said no operations had been disrupted by the intrusions, but they would not comment on whether any data had been stolen.
This story was first published by Computer Weekly