An　experimental　study　was　carried　out　to　investigate　the　mitigation　effect　of　vertical　walls　on　a　wharf　model　subjected　to　tsunami　bores.　Dam-break　waves　were　generated　in　a　flume　to　simulate　tsunami　bore　propagation,　the　bore　characteristics　were　observed,　and　the　tsunami　pressures　on　vertical　walls　and　a　wharf　model　were　measured.　Results　indicate　different　characteristics　for　bores　traveling　on　wet-bed　and　dry-bed.　The　tsunami　bore　impact　on　a　vertical　wall　was　shown　to　exhibit　four　stages,　and　the　time-history　of　the　pressure　exhibits　three　phases　accordingly.　Based　on　the　law　of　conservation　of　energy,　an　equation　for　estimating　the　pressure　exerted　on　the　mid-point　of　the　wall　was　proposed　with　coefficient　of　1.8-2.4,　and　found　to　be　suitable　in　this　experimental　range.　Based　on　experimental　data,　an　equation　of　the　mitigation　effect　of　vertical　walls　on　tsunami　was　proposed　as　a　function　of　the　inundation　depth,　the　wall　height　and　the　deck　height.　The　predicted　values　from　the　equation　are　generally　within　+/-　20%　of　the　measured　values.