Beldaur is an assembly constituency in Khagaria district in the Indian state of Bihar.
As per Delimitation of Parliamentary and Assembly constituencies Order, 2008, No. 150 Beldaur Assembly constituency is composed of the following: Beldaur and Chautham community development blocks; Banni, Jhiktiya, Samaspur, Maheshkhunt, Pakrail, Maira, Baltara, Pawra, Koela and Borna gram panchayats of Gogri CD Block.
Beldaur Assembly constituency is part of No. 25 Khagaria (Lok Sabha constituency).