Manjhi Assembly constituency is an assembly constituency in Saran district in the Indian state of Bihar.
As per the Delimitation of Parliamentary and Assembly constituencies Order, 2008, No. 114 Manjhi Assembly constituency is composed of the following: Jalalpur Community Development Block; Sarbisarya, Sitalpur, Tajpur, Adarsh Gram Bareja, Madan Sath, Ghorhat, Dumari, Jaitpur, Inayatpur, Nasira, Baleshra, Daudpur, Lejuar, Bangara, Sonbarsa, Marhan, Manjhi Purbi, Manjhi Pashchimi and Kouru-Dhouru Gram Panchayats of Manjhi CD Block; Karhi, Manikpura and Lauwa Kala gram panchayats of Baniapur CD Block.
Manjhi Assembly constituency is a part of No. 19 Maharajganj (Lok Sabha constituency).
In the 1969 Bihar Legislative Assembly election, Rameshwar Dut Sharma of the Indian National Congress won the Manjhi constituency. In the 1967 Bihar Legislative Assembly election, Ram Bahadur Singh of Samyukta Socialist Party won the Manjhi assembly seat. In the 1962, 1957, 1952 Bihar Vidhan Sabha elections, Girish Tiwary of the Indian National Congress (INC) won the Manjhi assembly seat.