To perform power-transmission by means of either of a power- transmission path passing through a belt from a torque converter output shaft or a power-transmission path not passing through the belt, depending on the travelling condition of a vehicle.

Power from a torque converter output shaft 3 is transmitted to a drive wheel by means of either of a power-transmission path passing through a continuously variable transmitting part 9 having a belt and pulleys or a power-transmission path not passing through the belt and passing-through a bypass shaft 21 provided to be separated from and parallel to a primary shaft through gears. Switching of these paths is performed by a power- transmission path switching device 22 provided between the torque converter output shaft 3 and the primary shaft 4. Forward- or reverse travel of a vehicle is performed by a forward-reverse switching device 45 provided at the bypass shaft 21.