Officials said the incident took place at about 10.00 am near the market area of Sangam village when the trooper, identified as constable Harikesh Prasad, was out for some personal work.
They said he was unarmed and was in civil clothes when some Naxals shot him from close range.
The jawan, working in the intelligence wing of the paramilitary force, was shifted to a hospital in the state capital here but succumbed to his injuries at 2 pm, they said.