The reason for his resignation was not known. Panmei could not be contacted as his phone was switched off.
Panmei is the fourth Congress MLA to quit the party and House since September. The Assembly polls in the state to be held in early 2017.
Manipur state Congress president T N Haokip told PTI that he had received Panmei's resignation letter.
"The reason for his resignation was best known to him only," Haokip said.
Assembly secretariat officials said the MLA from Tamenglong district submitted his resignation to Speaker Thokchom Lokeshwar Singh.
His resignation has not affected Congress' strength in the House as the party now has 48 members in the 60-member Assembly. However, the effective strength of the House is 52.