German education minister Annette Schavan resigned on Saturday over accusations of plagiarism.
The University of Duesseldorf on Wednesday ruled ms Schavan "systematically and intentionally" copied parts of her thesis, Person and Conscience, and withdrew the Ph.D it had granted her 33 years ago.
Ms Schavan, 57, reiterated her vow to fight the allegations, but said she did not want the claims to damage the office, the party or the federal government.
"I think today is the right day to leave my ministerial post and to concentrate on my duties as a member of parliament," she said on Saturday.
She was the second ally of Chancellor Angela Merkel to step down over plagiarism. Defence minister Karl-Theodor zu Guttenberg resigned in 2011.
At the time, Ms Schavan described his behaviour that as 'shameful'.
Chancellor Merkel told reporters: "I accepted this resignation with a very heavy heart."