VEHICLE-MOUNTED ELECTRIC COMPONENT COOLING STRUCTURE

[Problem to be Solved] Liquid is prevented from adhering to an internal component of a blower and a cooling target electric component.[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 blower 2 includes a cylindrical connection portion 2b communicating with the duct 3, the duct 3 includes a cylinder portion 32 that is cylindrically formed and allows the connection portion 2b of the blower 2 to be internally inserted, and an assembly 80 of the blower 2 and the duct 3 includes a foamed member 8 that surrounds an end portion of the cylinder portion 32 over an inner peripheral surface, an end surface and an outer peripheral surface of the cylinder portion 32.