To provide a bicycle that is compacted, can be lightened, is easily maintained, and can reduce cost, and a differential gear for the bicycle used for this.

In the bicycle and the differential gear, a main frame F is provided with a driving means 4 having a rotating shaft 3 for driving a wheel, a steering means 5, a front wheel 6F and rear wheel 6R of which at least one is two wheels, and the differential gear 8 capable of driving the two wheels by being driven by the rotating shaft 3 and being connected to two respective wheels for driving via a transmitting mechanism 7. The differential gear 8 comprises umbrella-like first gears 10 pivoted by a spindle 9 integrated with the rotating shaft 3 and extending radially and umbrella-like second gears 11 that mesh and face the first gear 10 on both sides and are pivoted rotatably coaxially with the rotating shaft 3. Each of the second gears 11 is connected to each of two wheels for driving via the transmitting mechanism 7.