Sivagangai is a state assembly constituency in Sivagangai district in Tamil Nadu. It is one of the 234 State Legislative Assembly Constituencies in Tamil Nadu, in India.
The current Member of Legislative Assembly (MLA) of the constituency is P. R. Senthilnathan from the AIADMK Party.
From the 1977 elections, the assembly seat was won by Dravida Munnetra Kazhagam (DMK) twice during the 1989 and 1996 elections; the Communist Party of India once during the 2006 elections; Indian National Congress three times during the 1977, 1980 and 1984 elections and the All India Anna Dravida Munnetra Kazhagam (AIADMK) three times during the 1991, 2001 and 2011 elections.