Since tire/road noise is dominant when a vehicle is traveling at a high constant speed, its reduction is important for the abatement of road traffic noise. It is well known that tire/road noise is obviously reduced by drainage asphalt pavement. It is considered that the reduction is due to the combination of the abatement of generated noise itself and the sound absorption of the road surface. The purpose of this study is to demonstrate that the pipe resonance in tread grooves is reduced on drainage asphalt pavement. The pressure fluctuation in tread groove under actual rolling condition was measured on two types of road surfaces, dense asphalt concrete pavement and drainage pavement. As a result, it was observed that the pipe resonance in tread groove is obviously reduced on drainage pavement. In addition, to examine the pipe resonance in tread groove in detail, the resonant frequency was calculated using BEM. As a result, it was shown that the shapes of the contact edges are important for calculating resonant frequency.