PURPOSE: To reduce noise as well as to improve durability of four-wheel or six- wheel drive cars by selecting rotational directions of deceleration mechanisms of output shafts for preventing the deceleration mechanisms unnecessary for power transfer from rotating at a high speed during a high speed rotation.

CONSTITUTION: When the first switching device 5 and a differential lock-up device 12 are connected and the second switching device 6 is disconnected, an input shaft 10 is rotated to rotate the second output shaft 50 without decelerating it via the first output shaft 33a, a center shaft 20 and a chain 9 of a sprocket 7. Even at this time, the first switching device 5 is disconnected from the input shaft 10, and a rotational direction and a speed are the same with a time of low speed transmission to the second output shaft 50 via a low speed counter drive gear 41, output gear 51 and to the first output shaft 33a via the second sprocket 8 and the first sprocket 7. This construction permits to reduce a noise source due to high-speed gear rotation, and improve the durability of bearings.