The 24-year-old had found the bomb on Sunday while walking in the Dachstein mountains, according to police in Lower Austria state.
She kept the shell in her belongings as a souvenir and declared it to customs officers when she came to the airport on Monday, who immediately rang the police.
A bomb disposal unit was called and in order to safely remove the device, the baggage hall and parts of the arrivals area were closed for around 15
There was no danger to passengers and no delays as a result, according to police.
The tourist was charged with public endangerment through negligence and given a four-figure fine.
More than 70 years after World War II and a century after World War I, unexploded bombs still regularly turn up across Austria and Germany, often
during construction work.