Disclosed is an electric-bicycle driving apparatus. The electric-bicycle driving apparatus includes a speed change mode operator to output a low-speed mode signal or a high-speed mode signal, a controller to receive the low-speed mode signal or high-speed mode signal output from the speed change mode operator and to output a first control signal corresponding to the low-speed mode signal or a second control signal corresponding to the high-speed mode signal, a generation-signal provider to provide a generation signal output from a generator, a stepping operation load booster to boost a load of the generation signal output from the generation-signal provider by receiving the first control signal or second control signal when the speed change mode operator outputs the low-speed mode signal or high-speed mode signal, and to send a stepping operation provider a resulting signal of the boost in a stepping operation signal corresponding to the low-speed mode signal or high-speed mode, and the stepping operation provider to receive the stepping operation signal from the stepping operation load booster, and to output a stepping operation drive signal corresponding to the low-speed mode signal or high-speed mode signal so as to drive pedals to be adapted to the high-speed mode or low-speed mode.