We have proposed the flap type gate for protection against storm surge and tsunami, and the studies for its hydraulic and hydrodynamic characteristics and design method of it are in progress. In this paper, two-dimensional hydraulic model tests on the scale of 1: 50 were carried out in the flowing water tank with the bore generator, and wave pressure and gate behavior required for designing of the flap type gate were revealed. Besides, function and performance of the flap type gate were examined in terms of disaster prevention against hydraulic bore by tsunami.