A hybrid driving unit (7) is mounted to a vehicle by coupling a coupling section (14d) at the front end of a casing member (14) with an internal combustion engine (5) and by mounting a mounting section (14c) at the rear end of the casing member (14) to a part (4a) of a body (4). Still more, a second electric motor (23), i.e., a heavy device, is disposed in the rearmost part among a first electric motor (20), a power splitting planetary gear (21), the second electric motor (23) and a transmission disposed on an axis (13) in the casing member (14). Thereby, the vibration occurring in the casing member (14) is suppressed.