PROBLEM TO BE SOLVED: To provide a service vehicle prime mover structure capable of ensuring the high draw-in capability of a radiator fan and the high exhaust capability of a dust discharge fan, suppressing the overheat of an engine, and ensuring the less frequency of maintenance and inspection work.SOLUTION: The object is attained by disposing an oxidation catalyst device 11 oxidizing unburned fuel contained in exhaust gas discharged from an engine (E) in an internal region of a vehicle body above the engine (E) along a front-rear direction, disposing an outdoor-air-draw-in radiator fan (20) capable of being switched between a driven state and a stopped state and an exhaust-gas dust discharge fan (30) capable of being switched between a driven state and a stopped state between the engine (E) and a radiator (50) cooling coolant circulating in the engine (E)； and providing a heat shield cover (95) between a side panel (6A) disposed a vehicle body internal side of a driver seat (6) in a side view and the oxidation catalyst device (11).
