Valarmathi is the Chairman of the Tamil Nadu Textbook and Educational Services Corporation and AIADMK's Literary Wing Secretary.
According to a hospital official, Valarmathi's condition is stable.
She is the sixth AIADMK leader to be infected with coronavirus.
Earlier, five lawmakers, including Higher Education Minister K. P.Anbalagan tested positive for the virus.
The other lawmakers who turned Covid-19 patients are: K. Palani (Sriperumbudur), Amman K. Arjunan (Coimbatore South),N. Sathan Prabhakar (Paramakudi) and Kumaraguru (Ulundurpet).
On the other hand, four lawmakers of the DMK too have tested positive in the state. They are -- K. S.Masthan (Gingee), R. T.Arasu (Cheyyur), Vasantham K. Karthikeyan (Rishivandhiyam), and J. Anbazhagan (Tiruvallikeni-Chepauk).
Anbazhagan succumbed to the infection last month.