As per Delimitation of Parliamentary and Assembly constituencies Order, 2008, No. 105 Siwan Assembly constituency is composed of the following: Siwancommunity development block includingSiwan Municipal Council; Lakri, Pakri, Aurae, Lakri Dargah, Kailgarh Uttar, Kailgarh Dakhin, Sunderpur and Hathigaigram panchayats of Barharia CD Block.[3]
Siwan Assembly constituency is part of No. 18Siwan (Lok Sabha constituency) .[3] The former MLA Vyasdev Prasad ofBJP had won this particular assembly seat 3 times in a row since 2005. Present MLA of Siwan is Shri Awadh Bihari Choudhary from RJD elected in 2020.