It is well known that when a compression wave generated by a high-speed train entering a tunnel propagates through the tunnel and arrives at the far exit, a “micro-pressure wave” is radiated from the exit portal toward the surrounding area. In addition, the entering/leaving train generates impulsive pressure waves outside the tunnel, which are radiated directly from the entrance/exit portal toward the neighboring area. We call the former a “tunnel entry wave, ” and the latter a “tunnel exit wave.” A similar phenomenon also occurs when the train passes an over-bridge in an open section. Here, we call this an “over-bridge passing wave.” Although, the over-bridge passing wave is usually weaker than the micro-pressure wave, it could cause an environmental problem with increases in the train speed. This paper reports the results of field measurement performed at a Shinkansen over-bridge on a canal to investigate the fundamental characteristics of the over-bridge passing wave.