The aim of this study is to investigate the reflection coefficient and the energy loss of tsunami as experimentally. The beach was built as a natural sandy one with grain diameter of 0.35 mm and the specific gravity of 2.63. The slopes of the beach were selected as 1/1.5, 1/5 and 1/8, respectively. As a result of experimental investigations, beach slope, tsunami run-up height, incident and reflecting wave heights, the characteristics of the beach material, and specific gravity of the water were determined as the parameters having the effect on both the reflection coefficient of tsunami and wave energy loss. These parameters are obtained as a dimensionless group via Buckingham’s Pi theorem. In addition, considering regression analysis, the relationship giving as dimensionless wave energy loss was proposed. The additional experiments were performed for different slopes that are 1/2.5, 1/3.5 and 1/6.5, respectively in order to verify the proposed equations derived from the study. Furthermore, the total energy values of the incident and the reflecting waves were calculated from the equation given in Coastal Engineering Manuel (CEM). These results were compared with the results of the proposed equations, and it was shown that there was a good agreement between the results.