The incident took place yesterday in Bagara, near the town of Diffa, an area that has repeatedly been targeted by Nigeria's Boko Haram Islamists in recent days.
"On Monday, a 17-year-old suicide bomber was shot dead in Bagara after trying to detonate his explosives belt," the army said in a report seen by AFP.
"The suicide bomber did not succeed in blowing himself up," the report said, adding that a military explosives expert was seriously injured, apparently while defusing the device.
A police man was wounded but his injuries were not life-threatening, according to the report.
The attack was the second foiled suicide bombing in less than a week in southeast Niger, which is separated from Boko Haram's heartland in northeast Nigeria by a river.
A week ago, a female suicide bomber blew herself up in a market in Diffa, killing six people and injuring around 15.