PURPOSE: To reduce speed silently while to reduce projection into cabin by driving the front def composed of bevel gear groups in a four-wheel-drive vehicle having a lateral engine, while arranging the front def and one of rear wheel bevel gears coaxially.

CONSTITUTION: Driving force of engine is transmitted through a clutch to the input shaft 6 of transmission where it is speed changed properly and outputted through a drive sprocket 24 of output shaft 9 and a chain 8 to a transmission sprocket 28 fixed to the casing 27 of front def 7. Said driving force is transmitted to the short shaft 30 of casing 27 at the front def 7 then distributed to the left and right by bevel gears 31-34 to drive the front wheel. At the same time, if 2-4 exchange sleeve 46 is at the four-wheel-drive position for coupling both end sections 27a, 45a, rotation of casing 27 will cause driving of bevel gears 10, 11 for driving rear wheels and transmitted through propeller shaft and rear def to the rear wheels.