To provide a driving device whereby a three-wheel or four-wheel bicycle can go in reverse and can be lightly driven.

In this driving device for the bicycle, pulleys 7a and 7b are connected by a wire 4, reciprocating movements of pedals 5a and 5b are achieved, inertial force when the pedal 5a is stepped is stored by a spring 21, and starting of the pedal 5b is assisted.