A US army vehicle hit an improvised explosive device as it entered a firing range during a training exercise near the town of Oullam, south-west Niger, the army says.
There were no fatalities but the soldiers are "being evaluated", it adds in a statement.
The soldiers were travelling in a mine-resistant vehicle when the explosion happened.
The US is supporting Niger in its fight against Islamist militants in the region.
In 2017, four US soldiers and four Nigerian soldiers were killed in an ambush near the Malian border.