She spoke at a news conference in her Montreal-area riding of Gouin.
“I have to stop before I burn out,” she said in French.
“I made this decision with regret, but also with serenity.”
The 69-year-old is stepping away from politics immediately, giving up her seat at the National Assembly.
“Confidence in the strength of our foundation, confidence in that many others with take up the fight, confidence in our collective ability to build a better Quebec.”
“We have come a long way. Ten years ago, when we founded Québec Solidaire, I promised to give a voice to the voiceless, challenge the establishment and solve Quebec’s political gridlock,” David said in English.
“I am proud of what we achieved. Nothing honoured me more that serving the people of Gouin for the last five years.”
David will not be accepting her departure bonus.
She was first elected to the National Assembly in 2012.