A driving force transmission apparatus is provided for a twin clutch
transmission with two clutches, that are controlled a gear change control
without a torque cutting out to reduce slapping sounds of the gears by
performing a pre-shift operation before the gear shift control. For
instance, in an up-shift operation from second speed to third speed, the
clutch that transmits torque to the third speed gear set is slip-engaged
and one gear of the third speed gear set is connected through a
synchronous engagement device to a countershaft. During the pre-shift, a
sub torque transmission path that is formed transmits engine torque of
the engine, a crankshaft, the clutch, a first input shaft, the third
speed gear set, the countershaft, and a differential gear system,
preventing the first input shaft from becoming idle and the slapping
sound of the gears in an engagement part of the third speed gear set.