VEHICLE-MOUNTED ELECTRIC COMPONENT COOLING STRUCTURE

[Problem to be Solved] The layout flexibility is improved, and sound propagation to an occupant compartment is reduced.[Solution] A vehicle-mounted electric component cooling structure includes: a ventilation portion 1 that has a ventilation hole 11 penetrating a wall 10 forming an occupant compartment S1 of a vehicle; a blower 2 that is provided in a rear region of the vehicle and causes an air flow for cooling a predetermined electric component P in the rear region; and a duct 3 that forms a flow path extending from the ventilation portion 1 to the blower 2. In the vehicle-mounted electric component cooling structure, the duct 3 includes a cylindrically formed reference tube portion 33, and a plurality of bulging tube portions 34 (34A and 34B) that bulge outward at an outer surface of the reference tube portion 33 and are cylindrically formed.