A transfer input shaft 51 of a transfer device 5 of a power transmission system PT has a first connection hole 51a that extends in a rotational axis direction from an end face on the side of a transfer input gear 55 that meshes with a final driven gear 42, and that connects the inside of a transmission case 61 and the inside of a transfer case 53. The transmission case 61 has a rib 62 that receives lubricating fluid scraped up by a final driven gear 42, and guides it toward the first connection hole 51a, in a position facing the end face of the transfer input shaft 51.