Official sources said personnel of 11 Gorkha Rifles were on patrol duty when the bomb, which was attached to a culvert, exploded at around 6:40 AM killing a jawan on the spot and injuring two others seriously.
It was not immediately known whether the suspected insurgents used remote-controlled device or a timer.
The explosion occurred about 6 km from Churachandpur police station and about 50 km south of the state capital, the sources said.
No individual or group immediately claimed responsibility for the incident which is the first major attack on army personnel this year, the sources added.