A bottom cover includes a plate portion including an inner-peripheral-edge portion defining an inlet, and a cooling duct including an upper wall and a pair of right and left sidewalls. The upper wall includes an upper-wall front portion inclined upward in the vehicle-height direction at a predetermined inclination angle, an upper-wall rear portion inclined upward in the vehicle-height direction at an inclination angle larger than the predetermined inclination angle of the upper-wall front portion, and the first upper-wall bent portion located at a boundary between the upper-wall front portion and the upper-wall rear portion. The rear ends of the right and left sidewalls, the rear end of the inner-peripheral-edge portion, and the rear end of the upper wall define an outlet.