Sonbarsha is an assembly constituency in Saharsa district in the Indian state of Bihar. It has been reserved for scheduled castes since 2010. Earlier, it was an open seat.
As per Delimitation of Parliamentary and Assembly constituencies Order, 2008, No. 74 Sonbarsha Assembly constituency (SC) is composed of the following: Sonbarsha, Patarghat and Banma Itahri community development blocks.
Sonbarsha Assembly constituency is part of No. 13 Madhepura (Lok Sabha constituency) .
Detailed Results at: https://results.eci.gov.in/ResultAcGenNov2025/ConstituencywiseS0474.htm
In the 2010 state assembly elections, Ratnesh Sada of JD(U) won the Sonbarsha assembly seat defeating Sarita Devi of LJP. Contests in most years were multi cornered but only winners and runners up are being mentioned. Kishor Kumar, Independent, RJD in October 2005 and Ashok Kumar Singh of RJD in February 2005. Ashok Kumar Singh defeated Kishor Kumar Singh, Independent, in 2000. Ashok Kumar Singh of JD defeated Tej Narayan Yadav, Independent, in 1995, and K.K. Mandal of Congress in 1990. Surya Narayan Yadav of aLD defeated Tej Narayan Yadav of CPI in 1985. Surya Narayan Yadav of Congress (U) defeated K.K. Mandal of Congress in 1980. Ashok Kumar Singh of JP defeated Surya Narayan Yadav, Independent, in 1977.