Anomalous loud sounds like booms were heard in a wide area in the Kanto region, Japan on June 16, 2003. Since the sky was thickly clouded, the source of the sounds, which was supposed to be a meteoroid penetrating the atmosphere, was hardly witnessed and photographed. It was recorded by only one video camera. We searched the shockwaves from the meteoroid recorded by a dense seismographic network. Shockwave signals were identified at 40 stations of the network deployed in the region. We report here the trajectory of the meteoroid determined by an analysis of seismic data. Combining the trajectory with the video camera data, we determined the precise velocity of the bolide in the atmosphere.