Ringstorff, 68, a centre-left Social Democrat, is the longest-serving state premier in what was Germany's formerly Communist east. He has held the office since 1998.
Ringstorff said the decision was not easy. Citing his age - he will turn 69 years old in September - and his 19 years in politics, he said holding office has taken all his strength. He said he looks forward to spending more time with his wife and family.
"Taking responsibility for your state also means passing on the baton at the right moment," Ringstorff said. "I think it is time for me to shift down a few gears."
Ringstorff declined to name a successor but said the state parliament could choose a new leader on October 6. Minister for Social Affairs Erwin Sellering, 58, is considered a favourite to replace him.
The Social Democrats have suffered a number of recent setbacks in the eastern Baltic Sea state, with Ringstorff's internal critics accusing him of having become to tired for the job.