The emission of wear particles from automotive brake friction materials is subject to Euro 7 regulations and is an important issue to be considered in the design process of friction material composition. We have measured the emission of wear particles from various types of friction materials on an inertial brake dynamometer. These results show that the emissions of PM2.5 and PM10 from NAO friction materials are significantly lower than those from low steel friction materials. Although most of the measurements were carried out with disc brakes, we tested and measured drum brakes, which are different braking system, in the same procedure. The drum brake was presumed to emit less wear particles than the disc brake because the friction material of drum brake is covered by a backing plate and a brake drum and is not fully exposed. However, the amount of wear particles emitted from drum brakes was close to the results of some disc brakes. In addition, the amount was depended on the condition of the drum brake, such as clearance between the brake drum and the backing plate, or degree of opening of access or maintenance holes of the backing plate. Based on this experimental background, this study focuses on the particle emissions of drum brake and presents the results of CFD simulation with parametric study. The outcome from CFD show similar trends to the actual test, therefore CFD is capable method for qualitatively grasping wear particle emissions performance of friction materials.