To improve assemblability of transfer chain by providing a drive sprocket, provided in a device for transmitting driving force of a main shaft to a transfer output shaft, to be fixed to a main shaft via a bush.

This device mounted on a four-wheel drive vehicle transmits a driving force of a main shaft 42 to a transfer output shaft 56 via a drive sprocket 60, a driven sprocket 62 and a transfer chain 64. The drive sprocket 60 is fixed to the main shaft 42 in splined engagement via a bush 66. In assembling the transfer chain 64, the drive sprocket 60 is penetrated in the main shaft 42 without using the bush 66 and located aslope at the vicinity of the transfer output shaft 56. Therefore, a distance between the drive sprocket 60 and the driven sprocket 62 is reduced and the chain 64 can easily be engaged with these two sprockets. Then the chain 62 moves to an normal position after the bush 66 is fitted.