The 43-year-old man from Burgenland told a court in the Austrian city of Eisenstadt that he had not realised he was holding the 60 centimetre long knife when he stepped out of the car following a dispute with another driver.
The machete, which he said he used to cut wood shavings, had fallen forward when the car braked and he said had picked it up as he had stepped out to talk to the other driver.
The other driver - a 42-year-old man - claimed that his opponent threatened to cut off his head with the knife and slapped him because he was annoyed about having to brake suddenly when the younger driver pulled into a road from a car park.
The 43-year-old, who claimed the other driver insulted him, admitted to the slap but denied he threatened the man with the knife. A policeman called to the scene confirmed, however, that the slapped man appeared very frightened.
As well as the sentence - which the 43-year-old is appealing - he was also made to pay a €50 fine.
Speaking in court he said he wished he had not slapped the man.
"That was a mistake. I should have stayed seated in my car and driven on," he said.