To secure a power propulsion unit with a driving force regulating mechanism, which makes use of the power transmission structure of a four-wheel drive vehicle, and suited to a two-wheel drive vehicle mounted with a transverse engine.

This propulsion unit is provided with a transverse engine 1 of a four-wheel drive vehicle turning to the same layout as a two-wheel drive vehicle, a transmission 3 and two differential gears 9 and 5, and in this constitution, a housing 25 housed with a driving force regulating mechanism 11a, regulating a distribution of driving force in both symmetrical wheels, is attached to a mounting surface 8 being made up in a differential housing 6 of these differential gears 9 and 5. With this, a power propulsion unit with the driving force regulating mechanism 11a suited to the two-wheel drive vehicle is securable without requiring new parts, insofar as possible.