Muthusamy and others were found hanging in their house this morning by neighbours who peeped in after noticing that the door remained locked for a long time.
The other deceased were the farmer's mother, 11-year old daughter and 4-year old son. His wife had gone to a nearby village to attend a festival, they said.
Muthusamy, who had taken four acres of land on contract, was upset as he could not get expected returns from farming.
A preliminary inquiry revealed that financial burden was the reason for the extreme step, police added.