PURPOSE: To protect driving system parts such as a transmission and a transfer device from heat radiated from exhaust system parts.

CONSTITUTION: An engine 5, a transmission 6 and a transfer device 7 are disposed on the same axis extended in the longitudinal direction of a body. A propeller shaft 9 rotated receiving output from the transfer device 7, and a differential gear 11 receiving the output of the propeller shaft 9 so as to distribute driving force to driving wheels are disposed on an axis extended parallel to the above-mentioned axis, at its side. An exhaust system part 13 is disposed by the side of the propeller shaft 9, in an opposite side position to the transmission 6 with the propeller shaft 9 in between. A power plant frame 14 connecting the transfer device 7 to the differential gear 11 is erected between the exhaust system part 13 and the propeller shaft 9. This power plant frame 14 is provided with a side face 14a large enough to block heat conduction in the air moving toward the transmission 6 from the exhaust system part 13.