"I hereby tender my resignation as Minister i/c Power, GAD and CnRD w.e.f. from today the 4th December, 2017 on personal grounds," Ymbon said in a letter to Chief Minister Mukul Sangma.
Mr Ymbon was sworn in as Minister in August this year.
Sources close to him said that he would not seek re-election on Congress ticket for the state Assembly elections due early next year.
Three other senior leaders of the party including party president and four times chief minister D D Lapang and two cabinet ministers have also announced they are not contesting next year's assembly elections.