"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.
At least six other Congress legislators including former deputy chief minister Rowell Lyngdoh and his cabinet colleagues Prestone Tynsong and Sniawbhalang Dhar have announced that they would not seek Congress party ticket for 2018 Assembly elections.
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.