A 230-kilogram bomb left behind from the Vietnam War was found Wednesday beside a national highway in the north-central province of Nghe An.
The explosive was found more than two meters below ground by workers of a company owned by the Ministry of Defense, online newspaper Dan Tri reported.
They were checking for unexploded ordnance (UXO) on National Highway 15A to enable work to expand it.
They deactivated the bomb and moved it to another site.
Local authorities said the highway was heavily bombed by the US during the Vietnam War which ended in 1975.
Around 6.6 million hectares, or more than a fifth of Vietnam's land area, contains UXO, according to official figures, with a mere 300,000 ha cleared so far.
Experts estimate it will take hundreds of years and billions of dollars to completely get rid of the remaining bombs, shells, and landmines.
Since 1975 UXOs have killed more than 40,000 people and injured 60,000.