To provide a compact and versatile driving force switching mechanism.

In this driving force switching mechanism, a first shaft 18 which is an input shaft of a differential 20 of one of pairs of wheels, a second shaft 17 for transmitting driving force from a driving source 1 and clutch mechanisms 19, 25, 26, 28 capable of connecting/detaching the first shaft 18 and the second shaft 17 with/from each other are formed within a final reduction gear 5.