PURPOSE: To cool an operating oil tank and a fuel tank at a low cost further without causing enlarging a size by rationally utilizing cooling discharge air of an engine with a simple structure, in a prime mover part structure for a work vehicle, providing an engine storage part of storing the engine and a tank storage part of storing the operating oil tank and the fuel tank, and arranging these parts in an L shape as viewed in a plan.

CONSTITUTION: An air control plate 16 for guiding partly cooling discharge air of an engine to a tank storage part is provided in an engine storage part 12, and further an operating oil tank 13 of the tank storage part is arranged so as to be in the upstream relating to cooling discharge air of the engine 11.