Hi,
Eligibility for admission to MTech at IIT Madras is that you  either have to qualify GATE or should have graduated from IIT.
Read full details here
https://engineering.careers360.com/articles/iit-madras-mtech-admission

Hai Mona, 

You must clear GATE exam with good score.

Complete your undergraduate programme with first class degree.

For further reference check this below link

https://www.google.co.in/amp/s/engineering.careers360.com/articles/iit-madras-mtech-admission%3famp