To provide an air conditioning duct mounting structure with a screw fastening structure discontinued.

An air conditioning duct 20 is retained by a bracket 12 formed by cutting and raising a part of a sandwich panel 11 integrated with a cowl panel 10. A usual structure fixing the air conditioning duct 20 with screws, thereby can be eliminated and a usual bracket 21 formed as one body with the air conditioning duct 20 can be eliminated. Accordingly, it is allowed to form the air conditioning duct 20 with sound absorbing soft material (for example expanded polypropylen) to absorb noise with the air conditioning duct 20.