A power transmission unit for a vehicle is provided. In the power transmission unit, a continuously variable transmission to alter a speed ratio continuously is disposed between an input shaft to which a torque of a prime mover is inputted and an output shaft rotated by the torque transmitted from the input shaft. A first gear train that transmits the torque to propel the vehicle in the forward direction is arranged parallel to a second gear train that transmits the torque to propelling the vehicle backwardly. The power transmission unit is comprised of: a first clutch device that selectively allows a torque transmitting route from the input shaft to the output shaft via the first gear train to transmit the torque therethrough; a dog clutch that switches the torque transmitting route from the input shaft to the output shaft between a continuously variable speed change route in which the torque is transmitted through the continuously variable transmission and a reverse route in which the torque is transmitted through the second gear train; and a second clutch device that connects and disconnects both of the continuously variable speed change route and the reverse route to/from at least any one of the input shaft and the output shaft.
