A balanced bridge electric gear-shifting mechanism comprises a signal input stage, a balanced bridge circuit and a signal output stage. The mechanism, by means of inputting different up and down gear signals to enact an analog gear-shifting apparatus to generate different voltage potentials, effectively improves the drawbacks of wrong gear shifting induced by a conventional digital gear shifting apparatus for wrongly touching the up and down shifting gear, so as to reduce the gear-shifting duration, enhance the gear-shifting smoothness, and enhance the system reliability and stability.