The incident took place when Chinnaram, accompanied by two constables, had gone to his field that falls under Farsegarh police station area, around 350km away from the state capital.
The other police jawan Budhram Toke, who was seriously injured in the attack, was later taken to the district hospital.
According to police, Chinnaram was a prominent leader during the erstwhile Salwa Judum movement and was on the hit-list of the ultras for a long time.
He was earlier attacked at least three times by the Maoists, following which, he was provided police protection, sources added.
Salwa Judum, an anti-Maoist civil militia, was disarmed and disbanded in the state following the Supreme Court order declaring as illegal and unconstitutional the deployment of tribal youths as Special Police Officers in the fight against the Maoist insurgency.