Jharkhand Assembly Speaker Dinesh Oraon took the decision as the Ramgarh Sub-divisional Judicial Magistrate had sentenced Prasad to three-years imprisonment on January 31, it said.
The release said under section 8 of the Peoples Representation Act, the membership of the House ceases with immediate effect if the prison term is two years or more than two years.
Prasad represented Gomia on JMM ticket.
On January 31, Ramgarh sub-divisional judicial magistrate, R P Mala had convicted Prasad and three others and sentenced them to three years rigorous imprisonment
The theft case was lodged with Rajrappa police station of Ramgarh district in 2010.