Drive unit for a vehicle

A drive unit for a vehicle includes first and second couplings, transmit / interrupt the rotational power from a primary reduction gear mechanism to first and second main shafts and are provided at respective ends of the first and second main shafts, said multi-speed gear trains between the counter shaft and the first and second main shafts be selectively established. Such a drive unit may be provided with a smaller number of components and a simple structure without their magnification. [Solution] A primary reduction gear (45) comprises: on a crankshaft (18)-provided drive gear (46); a first driven gear (73) from a first main shaft (19) is held at a position adjacent to a first clutch (47A) for relative rotation therewith and with the drive gear (46) meshes; an intermediate drive gear (74), which rotates with the first driven gear (73); an idle gear (75) meshing with the intermediate drive gear (74) and from the counter shaft (21) is held for relative rotation therewith; and a second driven gear (76), which is held by the second main shaft (20) for relative rotation therewith and with the idle gear (75) engages.