The coastal Takamatsu-city was flooded by the storm surge by the typhoon 0416 The maximum tide T P+2 46 m was recorded at the Takamatsu Port at 23 00 in Aug 30, 2004 The authors started the observation from the beginning of the flood by storm surge in the western Takamatsu-city The flood depth was measured at more than 700 points from flood marks, and the maximum depth is 172 centimeters The process of inflow from the coast to the inland through the underpass, has been clarified by the observation and the hearing research The flood districts were not controlled by the sea level and/or back current along river but the presence of channel such as underpass