Chief Election Officer Sunil Gupta said the polling started at 7 AM and was being conducted peacefully. The election has been necessitated by the death of Trinamool Congress MP Ambika Banerjee.
Being held in the aftermath of the Saradha chitfund scam which has defrauded thousands of investors, the polls assume importance as a pointer to the upcoming panchayat elections.
The main contest will be a triangular one between the TMC, Congress and the CPI(M) though there are 13 candidates in the fray.
The Trinamool Congress has fielded former India football captain Prasun Banerjee, the Congress has given a chance to lawyer Sanatan Mukherjee and CPI(M) to Sridip Bhattacherjee, a former party district secretary.
Though BJP is not contesting on the instructions of national president Rajnath Singh, seen as a move to keep the door ajar for the TMC, a former NDA ally, local BJP leader Ranjan Pal is in the fray as an independent.
In 2009, the BJP had bagged 37,723 votes in the seat, which was 3.8 per cent of the total votes polled. The Congress and the TMC, which have fallen apart, had fought the LS seat jointly in 2009. The TMC had emerged the winner.
The CPI(M) is hoping to cash in on the division of votes between the TMC and the Congress, the latter having a strong presence in the constituency, an industrial and rural one, with a total electorate of 14,47,174.
For the Congress, the by-election is important as a defeat could mean a setback for the party before the panchayat polls as well as next year's Lok Sabha election.