The incident happened at noon when Nguyen Thanh Duong, 44, tried to cut open the shell he had discovered earlier on a hill in la H'Drai District.
The blast reportedly killed him instantly. 
Since the Vietnam War ended in 1975, unexploded ordnance (UXO) incidents have killed more than 1,500 people and maimed another 2,200 a year, according to official statistics.
While some were accidental, many happened when poor people tried to salvage scrap metal from bombs.