The jar was found on September 7 at the home of Vo Hong Son, 30, in Cua Lo Ward, local authorities said.
An excavator operator struck a hard object while digging and unearthed the jar, which broke during the process, revealing a large number of coins inside.
"The jar of coins weighed nearly 10 kg. Most of the coins were corroded and some had stuck together," Son said.
He said the coins bore characters resembling Chinese script and had either round or square holes in the centre.
The land where the jar was found has been in Son's family for generations, but there are no records showing whether the coins were buried by his ancestors, he said.
Son said he did not know the age, denomination or value of the coins and planned to keep them as a memento.
The broken ceramic jar was later given to someone who asked for it.
