Siraha 1 is one of four parliamentary constituencies of Siraha District in Nepal.

This constituency came into existence on the Constituency Delimitation Commission (CDC) report submitted on 31 August 2017.

[1]Siraha 1 incorporates Bhagwanpur Rural Municipality, Sakhuwanankar Katti Rural Municipality, Lahan Municipality, wards 2–6 of Laxmipur Patari Rural Municipality and wards 1 and 2 4,5,6of Dhangadhimai Municipality.

It encompasses the following Province No.

2 Provincial Assembly segment