Greek media reported the man left a suicide note in which he accused the government of slashing his pension to nothing before he killed himself in the city's Syntagma Square Wednesday, the BBC reported Thursday.
"I see no other solution than this dignified end to my life, so I don't find myself fishing through garbage cans for my sustenance," the note found by police read.
"The government has annihilated all traces for my survival, which was based on a very dignified pension that I alone paid for 35 years with no help from the state," Athens News reported the note said.
Demonstrations shifted from peaceful to violent after the suicide, witnesses said. Demonstrators gathered in the square Wednesday evening and protesters threw gasoline bombs at police, who responded by firing tear gas.
The man has not been officially identified but media reported he was a retired pharmacist with a wife and daughter, the BBC said.
Officials said depression and suicides were on the rise as austerity measures to deal with Greece's huge debts take effect. Thousands of civil service jobs have been cut, taxes have been raised, and pay, benefits and pensions have been reduced.
Greece's unemployment rate now tops 20 percent and more than 20 percent of the population live below the poverty line.
"This was a symbolic suicide. If it hadn't happened here, in the square, in front of Parliament, no one would notice," a bystander told The Wall Street Journal.
In a statement, Greek Prime Minister Lucas Papademos called the death "tragic."
"In these difficult hours for our society we must all -- the state and the citizens -- support the people among us who are desperate," he said.