In order to apply the hot-film sensor for the analysis of the aerodynamic noise source, we measured the noise source around anautomobile door mirror. CAA (Computational Aeroacoustics) was usedfor the comparison on thequantitative noise source. We clarified that the one of the features of the aerodynamic noise generated from the actual automobile door mirror by the wind tunnel test was the low frequency noise. The low frequency noise sources inthe CAAwereformed by the perturbation of the long wave length formed at the tip side of the door mirror. The friction velocitymeasured by the hot-film probe in the low frequency domain indicated the same tendency tothe CAA analysis.