The man identified only as Balu consumed poisonous substance inside Hazare's office last evening, a police official said.
He was rushed to a hospital with the help of Parner police who have lodged a complaint, he said.
An aide to Hazare said land dispute led the man, a farmer, to take the step.
Reacting to the incident, Hazare said matters like land disputes should be resolved in court and suicide wasn't a solution.