Flood control capability of a dry dam which is a flood control dam without a slide gate in a spillway was quantitatively estimated for a hydraulic bore. In recent years a dry dam has been reviewed and planned in some sites since impacts on natural environments of a dry dam are relatively small. A dry dam may have several noticeable characteristics. For example, it should reduce damage from a hydraulic bore which happens if landslide occurs and a natural sedimentation dam formed by sediments and rocks collapses or they fall into a dam reservoir filled with water. In this study, flood control capability of a dry dam for a hydraulic bore was investigated using a dimensional analysis and numerical simulations. As a result, this study enables us to estimate the quantitative flood control capability of a dry dam for a hydraulic bore.