M Muruganandam said he had joined the party to do public work in an honest manner.
Another senior leader of actor and politician Kamal Haasan-led Makkal Needhi Maiam (MNM) quit the party today, blaming lack of democracy and honesty.
Party general secretary M Muruganandam is the fourth senior-level functionary to resign and the second after former Vice President Dr R Mahendran to allege lack of democracy in the three year-old party.
In a tweet, Mr Muruganandam said he had joined the party to do public work in "honest and independent manner."
"But with no conducive situation for that today, I am quitting from all party positions as well as the primary membership," he added.
In his resignation letter uploaded on his Twitter handle, Mr Muruganandam alleged that in the past few days there was "no democracy" in the organisation.
"With no democracy prevailing in the party, I have decided it is not appropriate to continue in it anymore," he said.
He further alleged that MNM''s alliance with "weak parties" for the April 6 Assembly polls, in which the block lost, had severely dented its image.
Mr Haasan had joined hands with IJK and actor R Sarath Kumar-led AISMK.
Mr Muruganandam also charged some persons with "misleading" Mr Haasan and interfering in party affairs and alleged that "unilateralism" and "autocracy" had crept into the party.
Post its electoral drubbing, MNM suffered a jolt when its then vice president Mahendran quit the party, alleging lack of democracy even as Haasan said that his former deputy was about to be sacked but expressed joy that "a weed" has weeded itself out from the MNM.
Two other seniors-- Santhosh Babu and Padma Priya -- had also quit the party recently citing personal reasons. Mr Babu, a former IAS officer was then General Secretary (HQ) while Padma Priya was the state secretary.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)