The giant earthquake of Mw=9.3 and the induced tsunami in December 26, 2004 caused the catastrophic damage of infrastructures such as coastal structures, utilities and transportation facilities. In this study, hydraulic experiments considering similarity laws were carried out to clarify a tsunami wave load to a bridge deck, focusing on the clarification of the dependence of the bridge deck lateral movement on inundation height and wave velocity induced by plunging breaker bores and surging breaker bores. Maximum ratio of the drag force to the deck weight becomes 0.31 to 0.34 when subjected to plunging breaker bores, and becomes 0.43 to 0.48 when subjected to surging breaker bores, that indicates the boundary lateral loads by which the deck movement against static friction force induced between a deck and abutments occurs.
