Nancy Allan says that at the age of 62 and after 16 years in the legislature, she feels it is time to retire.
Allan held a number of ministerial portfolios over the years, including labour and education.
She was dropped from cabinet in 2013 by Premier Greg Selinger and supported Theresa Oswald in a leadership challenge that Selinger survived earlier this year.
Allan says that was not a factor in her decision.
Other members of the governing New Democrats who are leaving politics include Jim Rondeau, who was demoted at the same time as Allan, and former education minister Peter Bjornson.